Double walled pipe, jacking method and pipe end structure of leading pipe

ABSTRACT

There is provided a double walled pipe having an inner pipe and an outer pipe which is movable relative to the inner pipe in a longitudinal direction of the inner pipe. Acting on only the outer pipe with a pipe jacking power makes it possible to bury the double walled pipe, without damaging the rear end of the inner pipe and also generating an internal stress on the inner pipe. Consequently, it is avoided such a situation that even in use pinholes, cracks, etc. occur on the inner pipe, and thus it is possible to expect an execution with higher reliability.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a double walled pipe, for example, agas pipe or the like, having a double walled pipe structure, which issuitable for a jacking method in which an object is propelled under theground to be buried underground, and a jacking method thereof, andfurther to a pipe end structure of a leading pipe which is used forleading the double walled pipe when it is propelled underground.

2. Description of the Related Art

It happens that as a pipe which is buried underground for transporting,for example, the high pressure gas, a double walled steel pipe is used.In such a double walled steel pipe, there is slushed the concrete or thelike the space between the inner pipe and the outer pipe to maintain thestrength of the pipe. Further, to bury such a double walled steel pipeunder the ground, there may be adopted a so-called jacking method.According to the jacking method, burying of the double walled steel pipeis conducted in such a manner that a predetermined shaft is beforehanddug to propel the double steel pipe from the side wall of the shaft inthe longitudinal direction, but not to bury the double walled steel pipefrom the ground through open-cut of an elongated groove extended alongthe burying path.

FIGS. 35(A) and 35(B) are a side elevation and a section view,respectively, showing by way of example the conventional double walledsteel pipe which will be used in adoption of the jacking method asdescribed above.

Referring to FIGS. 35(A) and 35(B), a double walled steel pipe 31basically comprises an inner pipe 33, an outer pipe 35 and a concrete 37which fills up the space between the inner pipe 33 and the outer pipe35. Where a front end portion 33a and a back end portion 33b of theinner pipe 33 are not covered by the concrete 37 and thus exposed.

There are prepared a plurality of pieces of such double walled steelpipe 31, and those are propelled underground in a direction as shown bythe arrow in the figure. At that time, burying of those pipes isimplemented in the following manner. A back end plane 33d of thepreceding double walled steel pipe 31 and a front end plane 33c of thesubsequent double walled steel pipe 31 are coupled to each other andwelded, and then the welded portion is fitted with one having a ringconfiguration in which a ring is segmented into a plurality of pieces, aback end plane 35b of the outer pipe 35 of the preceding double walledsteel pipe 31 and a front end plane 35a of the outer pipe 35 of thesubsequent double walled steel pipe 31 are jointed each other, and thethrust is applied to the back end plane 33d of the inner pipe 33 of thesubsequent double walled steel pipe 31 and the back end plane 35b of theouter pipe 35 of the subsequent double walled steel pipe 31 so that thesubsequent double walled steel pipe 31 may propel in an arrow directionshown in FIG. 35 (A). This process is repeatedly conducted over andover. As a result, the coupled double walled steel pipes 31 are buriedunder the ground.

The use of the above-mentioned conventional double walled steel pipes,however, suffers from the following drawbacks. The propulsion of thedouble walled steel pipes may cause the back end plane 33d of the innerpipe 33 to be bent or injured, for example. Thus, prior to welding thistogether the inner pipe of the subsequent double walled steel pipe,there will be needed a process for reshaping the back end plane 33d.Further, the propulsion of the double walled steel pipes may cause theinternal stress to be derived on the inner pipe 33. Thus, there is afear such that for example, pinholes, clacks or the like will occur onthe inner pipes, while the double walled steel pipes are buriedunderground and used.

In the jacking method adopting the above-mentioned double walled steelpipes 31, it is preferable from the view point of strength to fill upwith the cement milk the space between the inner pipe 33 and the outerpipe 35 (or the fitted one in a ring shape) at a coupling portion of thedouble walled steel pipe 31 to the double walled steel pipe 31. However,it would be difficult to completely fill up the space without any gap.Thus, it happens that steel segments are inserted in a circumferentialshape, without conducting filling up, and then the double walled steelpipes are propelled. This case will, however, involve the problem as tothe strength of the coupling portion of the double walled steel pipes.

Further, as another jacking method of burying the double walled pipes,there is known a method in which only the outer pipe is propelled underthe ground, in order to prevent the occurrence of flaws on the innerpipe through which gas or water will flow, and thereafter the inner pipeis fed or forced into the outer pipe, and then the concrete or mortar isinjected into the gap between the inner pipe and the outer pipe to fixthe inner pipe and the outer pipe together. According to this method, asmentioned above, there are needed two processes, one of which is forpropelling the outer pipe under the ground, and another for feeding orforcing the inner pipe into the propelled outer pipe. Thus, according tothis method, it takes much time, and in addition the cost forconstruction will be increased. Therefore, according to this method,from the view point of the cost, it is common that a concrete pipe (Humepipe) is used as the outer pipe.

SUMMARY OF THE INVENTION

In view of the foregoing, it is therefore an object of the presentinvention to provide a double walled pipe capable of propelling freefrom occurrence of the internal stress on the inner pipe, and a jackingmethod using such a double walled pipe.

It is another object of the present invention to provide a pipe endstructure of a leading pipe which is used for leading the double walledpipe when it is propelled underground.

To achieve the above-mentioned objects, according to the presentinvention, there is provided a double walled pipe comprising: an innerpipe; and an outer pipe which is movable relative to said inner pipe ina longitudinal direction of said inner pipe.

As the outer pipe and the inner pipe, applicable are a concrete pipe(Hume pipe), a concrete steel pipe, a cast iron, a resin pipe, a resincoated steel pipe, a steel pipe, a square-shape pipe, etc.

It is preferable that a front end portion or a back end portion of saidouter pipe is equipped with a guide member for guiding a tip of saidouter pipe to be moved relative to said inner pipe, said guide memberbeing adapted to conduct an effective coupling of a preceding doublewalled pipe with a subsequent double walled pipe.

It is preferable that said guide member includes: a ring member having apart inserted into one end of said outer pipe and fixed to said outerpipe and other part to be inserted into another outer pipe which is tobe coupled with said outer pipe, said other part being projected fromsaid outer pipe in a longitudinal direction of said outer pipe and beingprovided with a groove surrounding the periphery of the ring member; andan O-ring having a flexibility for sealing a coupling portion of outerpipe-to-outer pipe, said O-ring being engaged with said groove.

It is preferable that said ring member is formed, at a tip end to beinserted into said other outer pipe, with a taper section which isgradually reduced toward the tip end.

It is preferable that said outer pipe is equipped with a check valve forpermitting a one-way flow from an interior of said outer pipe towards anexterior.

Here, as one (hereinafter, referred to as a "first aspect") of thepreferable aspects of a double walled pipe according to the presentinvention, it is acceptable that a double walled pipe according to thepresent invention is so arranged that there is provided, between saidinner pipe and said outer pipe, an intercalary material for covering theperiphery of said inner pipe in such a manner that the front end portionand back end portion of said inner pipe are exposed. As the intercalarymaterial, for example, concrete and mortar, etc. are available.

In this case, it is preferable to provide a lubricating layer and/or acushion material such as styrene foam, a corrugated sheet and the likebetween an outer wall of said intercalary material and an inner wall ofsaid outer pipe. Otherwise, it is acceptable to provide a lubricatinglayer between an inner wall of said intercalary material and an outerwall of said inner pipe, and in case where said intercalary material iscomposed of a plurality of layers, between the layer-to-layer which areadjacent to each other.

It is acceptable that the lubricating layer is a lubricating agent suchas a lubricating oil, also a chemical resin, for example, polypropylene,which serves to reduce a sliding resistance between the outer pipe andthe inner pipe, still also a pipe-shape object in which a metal or thelike is formed in a pipe configuration, still also both the lubricatingagent and the pipe-shape object. Incidentally, in case where thepipe-shape object is adopted, it is acceptable to provide such anarrangement that the pipe-shape object is fixed to an inner wall of theouter pipe so as to be slidingly movable together with the outer pipewith respect to the intercalary material, otherwise, to provide such anarrangement that the pipe-shape object is fixed to the intercalarymaterial so that the outer pipe may slidingly move with respect to thepipe-shape object, still otherwise, to provide such an arrangement thatthe pipe-shape object is fixed to none of the outer pipe and theintercalary material, so that when the outer pipe is slidingly movedwith respect to the intercalary material, the pipe-shape object isslidingly moved with respect to both the outer pipe and the intercalarymaterial.

It is preferable that said cushion material is made of a styrene foam.

It is preferable that said cushion material is a corrugated sheet, and abarrier material is provided between said corrugated sheet and saidintercalary material.

It is acceptable in the arrangement including said corrugated sheet andsaid barrier material that said barrier material is fixed to saidcorrugated sheet, and at least front end plane, with respect to a pipejacking direction, of said corrugated sheet is capped with a watertightcap.

It is preferable that there is provided, between said inner pipe andsaid outer pipe, an intercalary material for covering the periphery ofsaid inner pipe in such a manner that the front end portion and back endportion of said inner pipe are exposed; and said intercalary material isequipped with a grout hose insertion hole extending in a longitudinaldirection of said double walled pipe.

Here, as another (hereinafter, referred to as a "second aspect") of thepreferable aspects of a double walled pipe according to the presentinvention, it is acceptable that a double walled pipe according to thepresent invention is so arranged that there is provided, between saidinner pipe and said outer pipe, a ring member surrounding the peripheryof said inner pipe, said ring member being fixed to said inner pipe; andsaid outer pipe is supported in such a way that it is slidingly movablewith respect to said ring member.

In this case, it is preferable that said ring member is equipped with agrout hose insertion hole, and said double walled pipe further comprisesa grout hose extending through said grout hose insertion hole in alongitudinal direction of said double walled pipe.

Otherwise, it is acceptable to provide such an arrangement that saidring member is equipped with an insertion opening into which a grouthose insertion tube is inserted, and said double walled pipe furthercomprises a grout hose insertion tube having a filling agent flow hole,extending through said insertion opening in a longitudinal direction ofsaid double walled pipe.

It is acceptable in the arrangement including said grout hose insertiontube that said grout hose insertion tube is equipped with said fillingagent flow hole only at the front end portion and/or the back endportion of said grout hose insertion tube.

Here, still as another (hereinafter, referred to as a "third aspect") ofthe preferable aspects of a double walled pipe according to the presentinvention, it is acceptable that a double walled pipe according to thepresent invention is so arranged that the double walled pipe furthercomprises: a plurality of rib bands each having at least one elliptichole extending in a peripheral direction of said inner pipe, each ofsaid rib bands surrounding an outer periphery of said inner pipe, andpenetrating in a longitudinal direction of said inner pipe; and aplurality of auxiliary pipe arrangements each inserted into the elliptichole of the associated rib band in such a manner that it is slidinglymovable with respect to said elliptic hole, wherein said auxiliary pipearrangements have each a first coupling section and a second couplingsection at a front end portion and back end portion, with respect to apropellent direction, of the auxiliary pipe arrangement, respectively,said first coupling section being coupled with a back end portion, withrespect to the pipe jacking direction, of a preceding double walledpipe, and said second coupling section being coupled with a front endportion, with respect to the pipe jacking direction, of a subsequentdouble walled pipe.

In this case, said first coupling section and said second couplingsection are each typically equipped with a male screw and a female screwwhich are adapted for screw-operating each other.

Here, still as another (hereinafter, referred to as a "fourth aspect")of the preferable aspects of a double walled pipe according to thepresent invention, it is acceptable that a double walled pipe accordingto the present invention is so arranged that the double walled pipefurther comprises: a first check valve for permitting a one-way flow ofa back filling material from an interior of said outer pipe towards anexterior, a filling tube extending between said outer pipe and saidinner pipe in their longitudinal direction, a second check valve forpermitting a one-way flow of a back filling material from an interior ofsaid filling tube towards an exterior, a first back filling tube, oneend of which is connected to said first check valve, extending from saidfirst check valve to backwards with respect to a pipe jacking direction,and a second back filling tube, one end of which is connected to saidsecond check valve, extending from said second check valve to forwardswith respect to the pipe jacking direction, wherein said first checkvalve of a preceding double walled pipe and said second check valve of asubsequent double walled pipe are connected through said first backfilling tube of the preceding double walled pipe and said second backfilling tube of the subsequent double walled pipe and in additionthrough a connection tube at least a part of which has a flexibility. Inthis case, it is acceptable to provide such an arrangement that aplurality of said first check valves are provided in a longitudinaldirection of said outer pipe, and said second back filling tube isconnected to the plurality of said first check valves.

Further, according to the present invention, there is provided a jackingmethod of propelling underground through a side wall of a shaft a doublewalled pipe comprising an inner pipe, and an outer pipe which is movablerelative to said inner pipe in a longitudinal direction of said innerpipe, comprising the steps of:

connecting a back end portion of an inner pipe of a preceding doublewalled pipe of which a rear end projects to the shaft with a front endportion of an inner pipe of a subsequent double walled pipe to be newlypropelled;

moving forwards said outer pipe of the subsequent double walled pipewith respect to said inner pipe to couple a front end plane of saidouter pipe of the subsequent double walled pipe with a back end plane ofsaid outer pipe of the preceding double walled pipe; and

propelling underground the subsequent double walled pipe upon acting ajacking power on said outer pipe of the subsequent double walled pipe,but upon acting no jacking power on said inner pipe of the subsequentdouble walled pipe.

Here, as a first aspect of the above-defined jacking method according tothe present invention, wherein said double walled pipe furthercomprising an intercalary material, provided between said inner pipe andsaid outer pipe, for covering the periphery of said inner pipe in such amanner that the front end portion and back end portion of said innerpipe are exposed, and a grout hose insertion hole extending in alongitudinal direction, it is acceptable that said method furthercomprises the steps of:

connecting a rear end of a grout hose exposed from an opening of a backend of said grout hose insertion hole of a preceding double walled pipewith a tip of a grout hose exposed from an opening of a front end ofsaid grout hose insertion hole of a subsequent walled double pipe, saidgrout hose connection step being conducted between said inner pipeconnection step and said outer pipe moving step; and

filling with a filling material a space between said inner pipes andsaid outer pipes of the connected double walled pipes each other, bymeans of slushing the filling material into the connected grout hoseseach other, after repetition of said inner pipe connection step, saidgrout hose connection step, said outer pipe moving step and said pipejacking step in connection with a plurality of said double walled pipes.

In said filling step, it is preferable that the filling is executed insuch a manner that while the connected grout hoses each other aresequentially drawn, the rear end of the grout hoses is sequentiallypositioned at the connected portions of said connected double walledpipes so that the connected portions are filled with the fillingmaterial.

In the first aspect of the above-defined jacking method according to thepresent invention, it is acceptable to adopt such a scheme that in midcourse of the repetition of said inner pipe connection step, said grouthose connection step, said outer pipe moving step and said pipe jackingstep in connection with a plurality of said double walled pipes, thereis set up, after said inner pipe connection step, a step of executingsaid outer pipe moving step omitting said grout hose connection step;and in said filling step, the grout hoses are drawn from both sides ofthe front and rear of the pipe jacking direction.

Here, as a second aspect of the above-defined jacking method accordingto the present invention, it is acceptable that said method ischaracterized in that said inner pipe connection step, said outer pipemoving step and said pipe jacking step are repeatedly executed inconnection with a plurality of said double walled pipes, so that thereis formed such a state that a back end portion of an outer pipe of saiddouble walled pipe finally coupled is exposed in said shaft while saidinner pipe is projected by a predetermined length from the back endportion of said outer pipe;

the back end portion of said double walled pipe finally coupled, whichtakes said state, is capped with a protection tube of which one end isclosed with a cover, said protection tube having a diameter same as theouter pipe and a depth exceeding said predetermined length;

a bearing wall is constructed for covering the back end portion of saiddouble walled pipe finally coupled, which takes said state, and saidprotection tube with which said back end portion is capped, said bearingwall being contact with said side wall; and

said inner pipe connection step, said outer pipe moving step and saidpropelling step are repeatedly executed in connection with a pluralityof said subsequent double walled pipes, while causing said bearing wallto bear a reaction force of a jacking, so that the plurality of saidsubsequent double walled pipes are propelled underground from a sidewall which is located over against said side wall.

In the second aspect of the above-defined jacking method according tothe present invention, it is preferable that before the back end portionof said double walled pipe finally coupled, which takes said state, iscapped with the protection cap, a back end portion of an inner pipe ofsaid double walled pipe finally coupled is capped with a protection capwhich is spaced from the protection cap when installed.

Still further, according to the present invention, there is provided apipe end structure of a leading a pipe for leading a double walled pipe,which comprises an inner pipe, and an outer pipe which is movablerelative to said inner pipe in a longitudinal direction of said innerpipe, when said double walled pipe is propelled underground, said pipeend structure said leading pipe comprising:

a dummy pipe which is set up, when jacking, at the rear of an excavationapparatus with respect to an excavation direction, and is withdrawnafter jacking; and

an adapter tube of which a front end is fixed to the rear of said dummypipe with respect to the excavation direction, said adapter tube havinga rear end to which fixed is an insertion joint for positioning theouter pipe of said double walled pipe with insertion into the front endinside of said double walled pipe, and an inside to which fixed is astopper for positioning said inner pipe.

A double walled pipe according to the present invention has an innerpipe and an outer pipe which is movable relative to the inner pipe in alongitudinal direction of the inner pipe. Acting on only the outer pipewith a jacking power, using the jacking method according to the presentinvention, makes it possible to bury the double walled pipe, withoutdamaging the rear end of the inner pipe and generating an internalstress on the inner pipe as well. Consequently, it is avoided such asituation that even in use pinholes, cracks, etc. occur on the innerpipe, and thus it is possible to expect an execution with higherreliability.

According to the present invention, the double walled pipe is providedwith the above-mentioned guide member. This features makes it possible,when the outer pipe is slid, to absorb an error in misaligment betweenthe outer pipe-to-outer pipe, thereby coupling the tip-to-tip of theouter pipes with greater accuracy.

The guide member includes a ring member having a part inserted into oneend of said outer pipe and fixed to said outer pipe and other part to beinserted into another outer pipe which is to be coupled with said outerpipe, said other part being projected from said outer pipe in alongitudinal direction of said outer pipe. This feature makes itpossible to couple the outer pipe-to-outer pipe to be coupled withgreater accuracy, upon positioning therebetween. Further, there areprovided a groove surrounding the periphery of the ring member and anO-ring engaged with said groove. Hence, in a state that the ring memberis inserted into the outer pipe, the O-ring is in contact with the innerperiphery of the outer pipe, so that the O-ring seals the couplingportion of the outer pipe-to-outer pipe. Furthermore, the ring member isformed, at a tip end to be inserted into said other outer pipe, with ataper section which is gradually reduced toward the tip end. Thisfeature makes it possible to facilitation an insertion of the ringmember into the inner of the outer pipe.

According to the double walled pipe of the present invention, the outerpipe is equipped, at the front end or the rear end, with a check valvefor permitting a one-way flow from an interior of said outer pipetowards an exterior. This prevents water or earth and sand from enteringthe space between the inner pipe and the outer pipe during a pipejacking. Even if those foreign objects entered, they will be dischargedoutside of the outer pipe by a filling pressure in filling of thefilling material. Hence, the filling material goes sufficiently aroundthe space between the inner pipe and the outer pipe. Also the fillingmaterial itself flows out of the outer pipe through the check valve, sothat the over break space also near the outer wall of the outer pipe isfilled with the filling material, thereby providing the buried pipe withgreater toughness.

Further, in the first aspect of the double walled pipe according to thepresent invention, there is provided, between said inner pipe and saidouter pipe, an intercalary material for covering the periphery of saidinner pipe in such a manner that the front end portion and back endportion of said inner pipe are exposed; and a lubricating layer isprovided in at least one selected from among spaces between an outerwall of said intercalary material and an inner wall of said outer pipe,between an inner wall of said intercalary material and an outer wall ofsaid inner pipe, and in case where said intercalary material is composedof a plurality of layers, between the layer-to layer which are adjacentto each other. The provision of the lubricating layer makes it possibleto reduces a sliding resistance between the outer pipe and theintercalary material, thereby permitting the outer pipe to be reliablyslidingly moved.

Furthermore, in the first aspect of the double walled pipe according tothe present invention, there is provided a layer constructed of acushion material is provided between an outer wall of said intercalarymaterial and an inner wall of said outer pipe. The provision of thecushion material of layer makes it possible, when a misalignment betweenthe outer pipe-to-outer pipe or an error in size exists in theircoupling, to absorb those drawbacks, thereby reliably coupling thetip-to-tip of the outer pipes.

In this case, the provision of not only the cushion material of layerbut also the guide member may provide a double walled pipe which is moreexcellent in execution.

In a case where said cushion material is made of a styrene foam, it isacceptable to provide such an arrangement that the sytrene foam is fixedto an inner wall of the outer pipe so as to be slidingly movabletogether with the outer pipe with respect to the intercalary material,otherwise to provide such an arrangement that the styrene foam is fixedto none of the outer pipe and the intercalary material, so that when theouter pipe is slidingly moved with respect to the intercalary material,the styrene foam is slidingly moved with respect to both the outer pipeand the intercalary material.

In a case where a corrugated sheet is used as the cushion material, ifthere are adopted, as the intercalary material, objects which show aflowability at an initial stage, for example, concrete, mortar, etc.,the intercalary material will creep in the groove of the corrugatedsheet. Hence, the corrugated sheet does not serve as the cushionmaterial of layer. Thus, in order to cope with this problem, a barriermaterial is provided between the corrugated sheet and the intercalarymaterial, so that the corrugated sheet may serve as the intercalarymaterial.

Also with respect to a sliding in a case where the corrugated sheet isprovided as the cushion material of layer, it is the same as that in acase where the styrene foam is provided as the cushion material oflayer, and thus it is acceptable to provide an arrangement permitting asliding in any one or more selected from among spaces between the outerpipe and the corrugated sheet, the corrugated sheet and the barriermaterial, and the barrier material and the intercalary material.

To implement the execution, it happens that there is adopted a method inwhich a grouting disposal is practiced every a connecting portion of twodouble walled pipes coupled to each other is connected by one place. Ina case where the corrugated sheet is provided as the cushion material oflayer, if at least the front end plane, with respect to the pipe jackingdirection, of the corrugated sheet is equipped with a watertight cap, itis possible to avoid such an inconvenience, which encounters when thesubsequent new double walled pipe is connected to the preceding doublewalled pipe, that when the connected portion is subjected to thegrouting disposal, the grouting material is leaked through the spacebetween the outer pipe or the barrier material and the corrugated sheetto the rear end with respect to the pipe jacking direction.Incidentally, in a case where the watertight cap is equipped, thewatertight cap will come off through sliding of the corrugated sheet andthe barrier material. Hence, the corrugated sheet and the barriermaterial are fixed. It is preferable that the rear end plane, withrespect to the pipe jacking direction, of corrugated sheet is alsocapped with the watertight cap. This arrangement makes it possible toavoid such a situation that the grout material crepts in the spacebetween the outer pipe or the barrier material and the corrugated sheetwhen the connected portion is subjected to the grouting disposal,thereby reducing an amount of grouting material to be used.

Further, the double walled pipe according to the present invention isequipped with a grout hose opening. After connection of the innerpipe-to-inner pipe by means of, for example, welding or the like, thegrout hoses are connected to each other. This arrangement makes itpossible to fill the space between the inner pipes and the outer pipesof the double walled pipes coupled to each other, with the fillingmaterial, such as cement milk or the like, which is flowed into thecoupled grout hoses together, after a plurality of the double walledpipes are buried underground in accordance with a jacking method. Inthis case, the cement milk or the like fills up the space between theinner pipes and the outer pipes of the double walled pipes with respectto also the coupled portion thereof, thereby providing the buries pipeswith greater toughness.

According to the second aspect of the double walled pipe according tothe present invention, there is provided an arrangement which permits asliding between the ring member and the outer pipe. Acting on only theouter pipe with a jacking power makes it possible to bury the doublewalled pipe, without damaging the rear end of the inner pipe and alsogenerating an internal stress on the inner pipe. Consequently, it isavoided such a situation that even in use pinholes, cracks, etc. occuron the inner pipe, and thus it is possible to expect an execution withhigher reliability.

In the second aspect of the double walled pipe according to the presentinvention, it is necessarily required that the space between the outerpipe and the inner pipe are filled with the cement milk or the like, incase that the outer pipe is provided with a sufficient rigidity orstiffness. From the view point of a durability, however, it ispreferable that the spaces between the outer pipe and the inner pipe arefilled with the filling material. In this case, the provision of thegrout hose makes it possible to fill up the space between the outer pipeand the inner pipe in such a manner that when the double walledpipe-to-pipe are connected, the grout hose-to-hose are also connected,and after multiple double walled pipes are connected and propelled, afilling agent is supplied to the grout hose while the grout hose isdrawn. Alternatively, it is acceptable to provide such an arrangementthat instead of the grout hose, the grout hose insertion tube isprovided, and when the double walled pipe-to-pipe are connected, thegrout hose insertion tube-to-tube are also connected, and aftercompletion of the propulsion the grout hose itself is inserted into thegrout hose insertion tube.

According to the third aspect of the double walled pipe according to thepresent invention, the double walled pipe further comprises: a pluralityof rib bands each having at least one elliptic hole extending in aperipheral direction of said inner pipe, each of said rib bandssurrounding an outer periphery of said inner pipe, and penetrating in alongitudinal direction of said inner pipe; and a plurality of auxiliarypipe arrangements each inserted into the elliptic hole of the associatedrib band in such a manner that it is slidingly movable with respect tosaid elliptic hole. Said auxiliary pipe arrangements have each a firstcoupling section and a second coupling section at a front end portionand back end portion, with respect to a pipe jacking direction, of theauxiliary pipe arrangement, respectively, said first coupling sectionbeing coupled with a back end portion, with respect to the pipe jackingdirection, of a preceding double walled pipe, and said second couplingsection being coupled with a front end portion, with respect to the pipejacking direction, of a subsequent double walled pipe. By the way, it isconsidered that the auxiliary pipe arrangement-to-arrangement areconnected through, for example, a flexible tube having a flexibility. Inthis case, however, since concrete or the like passes through theflexible tube, the flexible tube bends owing to weight of the concrete.This will invite a poor passage of the concrete. In addition, since itis necessary to connect both the ends of the flexible tube to both theauxiliary pipe arrangements, respectively, there are needed twoconnection points. Thus, this arrangement involves such a problem thatthe field work becomes troublesome.

On the contrary, according to the third aspect of the double walled pipeaccording to the present invention, the auxiliary pipearrangement-to-arrangement are directly connected. Therefore, a passageof the concrete or the like is kept satisfactory comparing with theconnection through the flexible tube and the like. Further, the elliptichole, to which the auxiliary pipe arrangement is inserted, extends in aperipheral direction of the inner pipe. Hence, even if there occursduring the pipe jacking a relative rotation between the inner pipe ofthe preceding double walled pipe and the outer pipe thereof, and thusthe misalignment exists a little between the auxiliary pipearrangements, it is possible to reliably position the auxiliary pipearrangements, thereby readily coupling the auxiliary pipearrangement-to-arrangement.

Further, according to the fourth aspect of the double walled pipeaccording to the present invention, a first back filling tube, one endof which is connected to a first check valve of a preceding doublewalled pipe, and a second back filling tube, one end of which isconnected to a second check valve of a subsequent double walled pipe,are connected through a connection tube at least a part of which has aflexibility. Those back filling tubes connected in such a manner isviewed as an overall back filling tube. Hence, even if there occurs arelative rotation between the inner pipe and the outer pipe, thisrelative rotation may be absorbed by the flexibility of the connectiontube, thereby preventing the back filling tube from being damaged.Further, the double walled pipe according to the present invention areprovided with a first check valve for preventing earth and sand fromflowing into the back filling tube from an exterior of the outer pipe,and in addition a second check valve disposed between the back fillingtube and the filling tube. Hence, the second check valve prevents theconcrete entering the back filling tube from returning to the inside ofthe filling tube. Thus, it is possible to avoid such a situation that aninterior of the filling tube is stopped up with the concrete.Consequently, it is possible to effectively pass the concrete throughthe filling tube. In this manner, this filling tube can be used both forback filling to cover the outside of the outer tube with concrete andmiddle filling to fill the space between the outer pipe and the innerpipe with the concrete.

Here, there are provided a plurality of said first check valves in alongitudinal direction of the outer pipe. The plurality of said firstcheck valves may disposed suitably in accordance with soil conditions ofpoints at which the double walled pipes are buried. This feature makesit possible to enhance a reliability of the back filling.

According to the first aspect of the above-defined jacking methodaccording to the present invention, when the second aspect of the doublewalled pipe is practiced, in other words, when the double walledpipe-to-pipe, which are each equipped with the intercalary material, areconnected, the grout hose-to-hose are coupled, and after the pipejacking, the filing agent such as cement milk is flowed into the grouthose so that the connected portion of the double walled pipes is filledwith the grout hose. This feature makes it possible to implement acomplete filling on the connected portion of the double walled pipes,thereby providing the buried pipe with a sufficient toughness.

Here, usually, while the connected grout hoses each other aresequentially drawn, the connected portions are filled with the fillingmaterial. In this case, it is acceptable that the grout hoses are drawneither forwards or backwards with respect to the pipe jacking direction.However, in case that the pipe jacking span is long, it is acceptable toprovide such an arrangement that the grout hose-to-hose are notconnected at the center or its vicinity and the grout hoses are drawnboth forwards or backwards with respect to the pipe jacking direction.This arrangement preferably permits a parallel working for the filling.

According to the second aspect of the above-defined jacking methodaccording to the present invention, a back end portion of the doublewalled pipe finally coupled, which takes such a state that the back endportion of an outer pipe of the double walled pipe finally coupled isexposed in said shaft while said inner pipe is projected by apredetermined length from the back end portion of said outer pipe, iscapped with a protection tube of which one end is closed with a cover; abearing wall is constructed for covering the back end portion of saiddouble walled pipe finally coupled, which takes said state, and saidprotection tube with which said back end portion is capped, said bearingwall being contact with said side wall; and said inner pipe connectionstep, said outer pipe moving step and said pipe jacking step arerepeatedly executed in connection with a plurality of said subsequentdouble walled pipes, while causing said bearing wall to bear a reactionforce of a pipe jacking, so that the plurality of said subsequent doublewalled pipes are propelled underground from a side wall which is locatedover against said side wall. This feature makes it possible toeffectively utilize the concrete floor of the shaft through jacking thedouble pipes from the single shaft, and in addition to save a lot oftrouble for carrying jacking apparatuses.

Further, a pipe end structure of a leading pipe for leading a doublewalled pipe according to the present invention comprising: a dummy pipewhich is set up, when pipe jacking, at the rear of an excavationapparatus with respect to an excavation direction, and is withdrawnafter pipe jacking; and an adapter tube of which a front end is fixed tothe rear of said dummy pipe with respect to the excavation direction,said adapter tube having a rear end to which fixed is an insertion jointfor positioning the outer pipe of said double walled pipe with insertioninto the front end inside of said double walled pipe, and an inside towhich fixed is a stopper for positioning said inner pipe. This structurepermits the rear end-to-end to be readily welded. Thus, it is possibleto perform the welding in short time. Still further, according to thepipe end structure of a leading pipe of the present invention, thestopper for positioning the main pipe of the double walled pipe is fixedinside of the adapter tube. This arrangement prevents the main pipe fromentering inside of the leading pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side elevation of a double walled pipe accordingto an embodiment of the present invention, extending along thelongitudinal direction;

FIG. 2 is a sectional view of the double walled pipe shown in FIG. 1looking from the right side of FIG. 1;

FIG. 3 is an enlarged sectional side elevation of a portion circled by adashed line A shown in FIG. 1;

FIGS. 4(A)-4(F) are typical illustrations useful for explanation of ajacking method of burying underground the double walled pipe having thestructure shown in FIGS. 1 to 3;

FIG. 5 is a sectional side elevation of a double walled pipe accordingto the second embodiment of the present invention, extending along thelongitudinal direction;

FIG. 6 is a sectional view of the double walled pipe shown in FIG. 5looking from the right side of FIG. 1;

FIG. 7 is an enlarged sectional side elevation of a portion circled by adashed line B shown in FIG. 5;

FIGS. 8(A)-8(F) are typical illustrations useful for explanation of ajacking method of burying underground the double walled pipe having thestructure shown in FIGS. 5 to 7;

FIG. 9 is a view showing a state of a misalignment between the outerpipes;

FIG. 10 is a sectional side elevation of a double walled pipe accordingto the third embodiment of the present invention, extending along thelongitudinal direction;

FIG. 11 is a sectional view of the double walled pipe shown in FIG. 10looking from the right side of FIG. 10;

FIG. 12 is an enlarged sectional side elevation of a portion circled bya dashed line C shown in FIG. 10;

FIGS. 13(A)-13(E) are typical illustrations useful for explanation of ajacking method of burying underground the double walled pipe having thestructure shown in FIGS. 10 to 12;

FIG. 14 is a sectional side elevation of a double walled pipe accordingto the fourth embodiment of the present invention, extending along thelongitudinal direction;

FIG. 15 is a sectional view of the double walled pipe shown in FIG. 14looking from the right side of FIG. 14;

FIG. 16 is an enlarged sectional side elevation of a portion circled bya dashed line D shown in FIG. 14;

FIG. 17 is a perspective view of part of a ring member;

FIGS. 18(A) and (B) are a sectional side elevation of part of the ringmember and a front view of part of the ring member;

FIG. 19 is a partially enlarged view of a ring member as a constituentpart of the double walled pipe shown in FIG. 14;

FIGS. 20(A)-20(F) are typical illustrations useful for explanation of apropulsion execution procedure of burying underground the double walledpipe having the structure shown in FIGS. 14 to 19;

FIG. 21 is a sectional side elevation of a double walled pipe accordingto the fifth embodiment of the present invention, extending along thelongitudinal direction;

FIG. 22 is a sectional view taken along the line E--E of FIG. 21;

FIG. 23 is an enlarged sectional side elevation of a portion circled bya dashed line F of FIG. 21;

FIG. 24 is a sectional side elevation of a propulsion double pipeaccording to the sixth embodiment of the present invention, extendingalong the longitudinal direction;

FIG. 25 is a partially enlarged view of first check valves asconstituent parts of the double walled pipe shown in FIG. 24;

FIG. 26 is a sectional side elevation of a propulsion double walled pipeaccording to the seventh embodiment of the present invention, extendingalong the longitudinal direction;

FIG. 27 is a sectional view taken along the line G--G of FIG. 26;

FIG. 28 is an enlarged sectional side elevation of a portion circled bya dashed line H of FIG. 26, in a state that auxiliary pipe arrangementsare coupled together;

FIG. 29 is a sectional side elevation of a double walled pipe accordingto the eighth embodiment of the present invention, extending along thelongitudinal direction;

FIG. 30 is a sectional view taken along the line I--I of FIG. 29;

FIG. 31 is an enlarged sectional side elevation of a portion circled bya dashed line J of FIG. 29,

FIG. 32 is a view showing a state that a ring member has been insertedinto the rear end of the outer pipe of the front in a pipe jackingdirection;

FIG. 33 is a view useful for understanding a jacking method of a doublewalled pipe according to an embodiment of the present invention;

FIG. 34 is a view useful for understanding a pipe end structure of aleading pipe according to an embodiment of the present invention;

FIGS. 35(A) and 35(B) are a side elevation and a section view,respectively, showing by way of example the conventional double walledsteel pipe which will be used in adoption of the jacking method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, there will be described embodiments of the presentinvention.

FIG. 1 is a sectional side elevation of a double walled pipe accordingto an embodiment of the present invention, extending along thelongitudinal direction, FIG. 2 is a sectional view of the double walledpipe shown in FIG. 1 looking from the right side of FIG. 1, and FIG. 3is an enlarged sectional side elevation of a portion circled by a dashedline A shown in FIG. 1. Here, there will be explained, by way ofexample, a double walled steel pipe for gas.

FIGS. 1 and 3 show a preceding double walled pipe 1' which has beenpropelled underground and of which only a part of the rear end isprojected into a shaft, and a subsequent double walled pipe 1 which isto be coupled to the rear end of the the preceding double walled pipe 1'and to be propelled underground together with the double walled pipe 1'.These double walled pipes 1 and 1' each have the same structure.

The double walled pipe 1 comprises an inner pipe 2 constructed of asteel pipe having about 900 mmφ, an outer pipe 3 also constructed of asteel pipe having about 1200 mmφ, and concrete 4 as an intercalarymember for filling up the space between the inner pipe 2 and the outerpipe 3. The concrete 4 is equipped with, as shown in FIG. 2, a vinylchloride tube 5 to form a grout hose insertion hole or opening. A grouthose 6 is inserted into the vinyl chloride tube 5.

Further, as seen from FIG. 3, near the front end portion of the outerpipe 3 regarding the pipe jacking direction, there is provided a checkvalve 9 which serves to open when pushed from the inside of the pipe andto close when pushed from the outside of the pipe. A polypropylene tube7 is mounted around the concrete 4. A lubricant is coated between aninner wall of the outer pipe 3 and an outer wall of the polypropylenetube 7, so that the outer pipe 3 may slide relative to the concrete 4when the outer pipe 3 is secured in its longitudinal direction. Thefront end portion of the outer pipe 3 is provided with a guide ring 10as a guide member. While the back end portion is provided with a stopring 11 at its inner wall side. As will be described later in detail,when the outer pipe 3 of the double walled pipe 1 is forwardly slidrelative to the concrete 4, the guide ring 10 enters the inside of anouter pipe 3' of the double walled pipe 1' through a back end plane 3c'thereof, so that the top of the guide ring 10 is coupled to the stopring 11. In addition, a front end plane 3b of the outer pipe 3 of thedouble walled pipe 1 is coupled to the back end plane 3c' of the outerpipe 3' of the double walled pipe 1'. In this manner, the provision ofthe guide ring 10 makes it possible to reliably couple the outer pipes 3and 3' to each other, even if the misalignment exists a little betweenthe outer pipes 3 and 3', since an error is absorbed.

An outside face 2a of the inner pipe 2 is covered with a polyethylenemember. As shown in FIGS. 1 and 3, after a front end plane 2b of theinner pipe 2 of the double walled pipe 1 and a back end plane 2c' of theinner pipe 2' of the double walled pipe 1' are coupled to each other,these inner pipes are welded at their coupled portion. After thewelding, the portion undergone the welding is covered with apolyethylene tube.

FIGS. 4(A)-4(F) are typical illustrations useful for explanation of ajacking method of burying underground the double walled pipe having thestructure shown in FIGS. 1 to 3.

As shown in FIG. 4(A), assume that the preceding double walled pipe 1'has been propelled underground in accordance with a jacking method and apart of the rear end thereof is projected into a shaft. The subsequentdouble walled pipe 1 is prepared in connection with the preceding doublewalled pipe 1' of which a part of the rear end is projected into theshaft, and is disposed in such a manner that the front end plane 2b ofthe inner pipe 2 of the double walled pipe 1 and the back end plane 2c'of the inner pipe 2' of the double walled pipe 1' are coupled to eachother (refer to FIGS. 1 and 3).

In the next step, as shown in FIG. 4(B), the front end plane 2b of theinner pipe 2 of the double walled pipe 1 and the back end plane 2c' ofthe inner pipe 2' of the double walled pipe 1', which are coupled toeach other, are welded. The state after the welding is inspected using aX ray. When passing inspection, the portion undergone the welding iscovered with a polyethylene tube 20. Incidentally, as aforementioned,the outside face 2a of the inner pipe 2, also including portionsconcealed behind the concrete 4, is covered with the polyethylenemember.

In the next step, as shown in FIG. 4(C), the grout hoses 6 of the doublewalled pipe 1 and the double walled pipe 1', each being inserted intothe vinyl chloride tube 5, as shown in FIG. 2, used for insertion of thegrout hose, are connected to each other. Incidentally, with respect to apair of grout hoses which will be finally located at the middle or itsvicinity when a multiple connection of the grout is completed throughthe pipe jacking, they are left not to be connected so that theconnected grout hoses can be separately drawn half-and-half at the frontand rear in a pipe jacking direction, respectively.

Thereafter, the outer pipe 3 is slid forwardly relative to the concrete4 until it takes a state shown in FIG. 4(D) from the state shown in FIG.4(C), so that the front end plane 3b of the outer pipe 3 is coupled tothe back end plane 3c' of the outer pipe 3'.

In the next step, as shown in FIG. 4(E), a push wheel 21 is fitted tothe rear end of the double walled pipe 1 so as to couple with only therear end plane 3c of the outer pipe 3, a propulsion oil jack 22 is setto push the push wheel 21, and the double walled pipe 1 is propelledunderground, upon acting on the outer pipe 3 with the thrust, togetherwith the double walled pipe 1' and the further preceding double walledpipes. The front end portion of the first stage of double walled pipe ismounted with an excavation head (not illustrated), thereby jacking whiledigging.

After a series of processes as mentioned above is repeatedly applied fora number of double walled pipes, the cement milk is flowed into thegrout hose 6 (refer to FIG. 2) so as to fill the space between the innerpipe 2 and the outer pipe 3 at each of the connected portions of thedouble walled pipes, while the grout hose is drawn in such a manner thatthe top of the grout hose is sequentially disposed at the connectedportions of the double walled pipes. In this case, when the grout hose 6is drawn backwards in the pipe jacking direction, in order to preventthe cement milk from overflowing through the opening of the edge of thegrout hose insertion tube 5 of the preceding double walled pipes, it ispreferable to close the opening. Further, it is preferable, when thegrout hose 6 is drawn, to draw the grout hose 6 while the cement milk isflowed into the grout hose 6, so that the inside of the grout hoseinsertion tube 5 is also filled with the cement milk. When the spacebetween the inner pipe 2 and the outer pipe 3 at the connected portionis filled with the cement milk, water, earth and sand, etc., which enterbetween the inner pipe 2 and the outer pipe 3, are exhausted by thecement milk out of the outer pipe 3 via the check valve 9, and inaddition the cement milk itself also flows out via the check valve 9,whereby the outer wall of the outer pipe 3 is also covered with thecement milk, as shown in FIG. 4(F). Thus, it is possible to provide theunderground pipe with greater toughness, and in addition to prevent asettlement of the ground level.

The above-mentioned double pipe, which is buried underground, is adaptedto flow gas, by way of example, with a gas pressure 70 kg/cm², throughthe inside of the inner thereof.

FIG. 5 is a sectional side elevation of a double walled pipe accordingto the second embodiment of the present invention, extending along thelongitudinal direction. FIG. 6 is a sectional view of the double walledpipe shown in FIG. 5 looking from the right side of FIG. 5. FIG. 7 is anenlarged sectional side elevation of a portion circled by a dashed lineB shown in FIG. 5. Here also, there will be explained, by way ofexample, a double walled steel pipe for gas.

FIGS. 5 and 7 show a preceding double walled pipe 11' which has beenpropelled underground and of which only a part of the rear end isprojected into a shaft, and a subsequent double walled pipe 11 which isto be coupled to the rear end of the preceding double walled pipe 11'and to be propelled underground together with the double walled pipe11'. These double walled pipes 11 and 11' each have the same structure.

The double walled pipe 11 comprises an inner pipe 12 constructed of asteel pipe having about 900 mmφ, an outer pipe 13 also constructed of asteel pipe having about 1200 mmφ, concrete 14 as an intercalary memberfor filling up the space between the inner pipe 12 and the outer pipe13, and a styrene foam layer 18 using styrene foam as a cushionmaterial. The concrete 14 is equipped with, as shown in FIG. 6, a vinylchloride tube 15 to form a grout hose insertion hole or opening. A grouthose 16 is inserted into the vinyl chloride tube 15.

Further, as seen from FIG. 7, near the front end portion of the outerpipe 13 regarding the pipe jacking direction, there is provided a checkvalve 19 which serves to open when pushed from the inside of the pipeand to close when pushed from the outside of the pipe. A polypropylenetube 17 is mounted between an inner wall of the outer pipe 13 and thestyrene foam layer 18. A lubricant is coated between an inner wall ofthe outer pipe 13 and an outer wall of the polypropylene tube 17. Thisdouble walled pipes 11 is provided with a plurality of sliding portions,as a portion which permits the outer pipe 13 to slide when it is pushedin its longitudinal direction, such as a first portion between the outerpipe 13 and the polypropylene tube 17, a second portion between thepolypropylene tube 17 and the styrene foam layer 18, and a third portionbetween the styrene foam layer 18 and the concrete 14. The provision ofsuch a plurality of sliding portions makes it possible to expect a morereliable sliding relative to the concrete 14 and the inner pipe 12,comparing with for example a case where there is arranged in such a waythat a sliding of the outer pipe is permitted only between the outerpipe 13 and the polypropylene tube 17, having no styrene foam layer 18.While it is acceptable that the sliding occurs on any of the pluralityof sliding portions as mentioned above, FIGS. 8 and 9 show thestructure, assuming that the sliding occurs between the outer pipe 13and the polypropylene tube 17. The front end portion of the outer pipe13 is provided with a guide ring 20 as a guide member. While the backend portion is provided with a stop ring 21 at its inner wall side. Aswill be described later in detail, when the outer pipe 13 of the doublewalled pipe 11 is forwardly slid relative to the concrete 14, the guidering 20 enters the inside of an outer pipe 13' of the double walled pipe11' through a back end plane 13c' thereof, so that the top of the guidering 20 is coupled to the stop ring 21. In addition, a front end plane13b of the outer pipe 13 of the double pipe 11 is coupled to the backend plane 13c' of the outer pipe 13' of the double walled pipe 11'. Ifthe misalignment or an error in size exists between the outer pipes 13and 13', a positioning has to be conducted in a manner as will bedescribed later. According to the present embodiment, in such asituation, it is possible to facilitate the positioning work, sincethere is provided the styrene foam layer 18.

An outside face 12a of the inner pipe 12 is covered with a polyethylenemember. As shown in FIGS. 5 and 7, after a front end plane 12b of theinner pipe 12 of the double walled pipe 11 and a back end plane 12c' ofthe inner pipe 12' of the double walled pipe 11' are coupled to eachother, these inner pipes are welded at their coupled portion. After thewelding, the portion undergone the welding is covered with aanticorrosion polyethylene tube.

FIGS. 8(A)-8(F) are typical illustrations useful for explanation of ajacking method of burying underground the double walled pipe having thestructure shown in FIGS. 5 to 7.

As shown in FIG. 8(A), assume that the preceding double walled pipe 11'has been propelled underground in accordance with a jacking method and apart of the rear end thereof is projected into a shaft. The subsequentdouble walled pipe 11 is prepared in connection with the precedingdouble walled pipe 11' of which a part of the rear end is projected intothe shaft, and is disposed in such a manner that the front end plane 12bof the inner pipe 12 of the double walled pipe 11 and the back end plane12c' of the inner pipe 12' of the double walled pipe 11' are coupled toeach other (refer to FIGS. 5 and 7).

In the next step, as shown in FIG. 8(B), the front end plane 12b of theinner pipe 12 of the double walled pipe 11 and the back end plane 12c'of the inner pipe 12' of the double walled pipe 11', which are coupledto each other, are welded. The state after the welding is inspected by aX ray. When passing inspection, the portion undergone the welding iscovered with a polyethylene tube 30. Incidentally, as aforementioned,the outside face 12a of the inner pipe 12, also including portionsconcealed behind the concrete 14, is covered with the polyethylenemember.

In the next step, as shown in FIG. 8(C), the grout hoses 16 of thedouble walled pipe 11 and the double walled pipe 11', each beinginserted into the vinyl chloride tube 15, as shown in FIG. 6, used forinsertion of the grout hose, are connected to each other. Incidentally,with respect to a pair of grout hoses which will be finally located atthe middle or its vicinity when a multiple connection of the grout iscompleted through the pipe jacking, they are left not to be connected sothat the connected grout hoses can be separately drawn half-and-half atthe front and rear in a pipe jacking direction, respectively.

Thereafter, the outer pipe 13 is slid forwardly relative to the concrete14 until it takes a state shown in FIG. 8 (D) from the state shown inFIG. 8 (C), so that the front end plane 13b of the outer pipe 13 iscoupled to the back end plane 13c' of the outer pipe 13'.

Now, there will be explained such a case that a misalignment or the likeexists between the outer pipes 13 and 13', and thus the outer pipe 13can not be coupled properly with the outer pipe 13' through simplysliding forwardly the outer pipe 13.

FIG. 9 is a view showing a state of a misalignment between the outerpipes 13 and 13'.

In FIG. 9, the outer pipe 13 deviates upwards with respect to the outerpipe 13'. Hence, if the outer pipe 13 is simply slid forwardly (lefthand in the figure), the guide ring 20 will be coupled with the back endplane 13c' of the outer pipe 13'. Thus, in a case where such amisalignment exists, a L-like shaped member 40, as shown in the figure,which has a sufficiently greater toughness and rigidity in comparisonwith the outer pipe 13, is temporarily welded on the outer pipe 13', anda wedge 42 is urged between the member 40 and the outer pipe 13 slid inthe front. As a result, the front edge portion of the outer pipe 13 isbent downwards, so that the guide ring 20 may enter the inside of theouter pipe 13' when the outer pipe 13 is further slid forwardly. Inconnection with a positioning of the outer pipe 13, the provision of thestyrene foam layer 18 serves to more facilitate the positioning of theouter pipe 13, in comparison with a case where the concrete 14 is filledup to the portion of the styrene foam layer 18, since the styrene foamlayer 18 may be deformed. Thus, the positioning working efficiency isremarkably enhanced.

In this manner, after the outer pipes 13 and 13' are properly coupled toeach other, in the next step, as shown in FIG. 8(E), a push wheel 31 isfitted to the rear end of the double walled pipe 11 so as to couple withonly the rear end plane 13c of the outer pipe 13, a propulsion oil jack32 is set to push the push wheel 31, and the double walled pipe 11 ispropelled underground, upon acting on the outer pipe 13 with the thrust,together with the double walled pipe 11' and the further precedingdouble walled pipes. The front end portion of the first stage of doublewalled pipe is mounted with an excavation head (not illustrated),thereby jacking while digging.

Incidentally, while it has been described above that after the outerpipe 13 is slid forwardly, the propulsion oil jack 32 is set to push thepush wheel 31, it is acceptable that this setting is conducted prior tosliding of the outer pipe 13, and the outer pipe 13 is slid by thepropulsion oil jack 32.

After a series of processes as mentioned above is repeatedly applied fora number of double walled pipes, the cement milk is flowed into thegrout hose 16 (refer to FIG. 6) so as to fill the space between theinner pipe 12 and the outer pipe 13 at each of the connected portions ofthe double walled pipes, while the grout hose is drawn in such a mannerthat the top of the grout hose 16 is sequentially disposed at theconnected portions of the double walled pipes. In this case, when thegrout hose 16 is drawn backwards in the pipe jacking direction, in orderto prevent the cement milk from overflowing through the opening of theedge of the grout hose insertion tube 15 of the preceding double walledpipes, it is preferable to close the opening. Further, it is preferable,when the grout hose 16 is drawn, to draw the grout hose 16 while thecement milk is flowed into the grout hose 16, so that the inside of thegrout hose insertion tube 15 is also filled with the cement milk. Whenthe space between the inner pipe 12 and the outer pipe 13 at theconnected portion is filled with the cement milk, water, earth and sand,etc., which creep between the inner pipe 12 and the outer pipe 13, areexhausted by the cement milk out of the outer pipe 13 via the checkvalve 19, and in addition the cement milk itself also flows out via thecheck valve 19, whereby the outside face of the outer pipe 13 is alsocovered with the cement milk, as shown in FIG. 8(F). Thus, it ispossible to provide the underground pipe with greater toughness, and inaddition to prevent a settlement of the ground level.

FIG. 10 is a sectional side elevation of a double walled pipe accordingto the third embodiment of the present invention, extending along thelongitudinal direction.

FIG. 11 is a sectional view of the double walled pipe shown in FIG. 10looking from the right side of FIG. 10. FIG. 12 is an enlarged sectionalside elevation of a portion circled by a dashed line C shown in FIG. 10.Here also, there will be explained, by way of example, a double walledsteel pipe for gas. In these figures, the same parts are denoted by thesame reference numbers as those of the figures involved in the secondembodiment described above, and the redundant description will beomitted.

The double walled pipe 11 in FIG. 10 comprises concrete 14 as anintermediate member for filling up the space between the inner pipe 12and the outer pipe 13, a polypropylene tube 17 as a barrier material forcovering an outer wall of the concrete 14, and a hard vinyl chloridecorrugated sheet 25, as a cushion material, contacting with an outsideface of the polypropylene tube 17 and an inner wall of the outer pipe13. If the concrete 14 adheres to the hard vinyl chloride corrugatedsheet 25 and be hardened thereon, then it will be a cause of prohibitingthe hard vinyl chloride corrugated sheet 25 from being deformed. Thus,it will be difficult for the hard vinyl chloride corrugated sheet 25 toserve as the cushion material. In order to avoid such a drawback, thereis provided the polypropylene tube 17 between the hard vinyl chloridecorrugated sheet 25 and the concrete 14. As shown in FIG. 11, the hardvinyl chloride corrugated sheet 25 is fixed with vises 27 on thepolypropylene tube 17 and the concrete 14. As a result, when the outerpipe 13 is slid relative to the concrete 14, the sliding occurs betweenthe outer pipe 13 and the hard vinyl chloride corrugated sheet 25. Thevis 27 serves also to reinforce the concrete 14.

As shown in FIG. 12, near the front end portion of the outer pipe 13regarding the pipe jacking direction, there is provided a check valve19. The front end portion of the outer pipe 13 is equipped with a guidering 20 as a guide member. While the back end portion is equipped with astop ring 21 at its inner wall side. The front end plane and rear endplane of the corrugated sheet 25 each are capped with a blowingpolystyrene member 26 as a cap for cut-off water.

FIGS. 13(A)-13(E) are typical illustrations useful for explanation of ajacking method of burying underground the double walled pipe having thestructure shown in FIGS. 10 to 12.

FIGS. 13(A) and 13(B) show the similar processes as shown in FIGS. 8(A)and 8(B), respectively, and thus the explanation will be omitted.

As shown in FIG. 13(C), the grout hose 16, which is inserted into thevinyl chloride tube 15 shown in FIG. 11, is drawn so that the front endof the grout hose is located between the inner pipe 12 and the outerpipe 13, and the outer pipe 13 is slid forwardly relative to theconcrete 14. In this manner, the front end plane 13b of the outer pipe13 is coupled to the back end plane 13c' of the outer pipe 13'. At thattime, if a misalignment exists between the outer pipes 13 and 13', apositioning is conducted in the manner as aforementioned.

In the next step, as shown in FIG. 13 (D), after the outer pipes 13 and13' are properly coupled to each other, the cement milk is filled to theconnected portion of the double walled pipe 11 and 11'.

Since the front end plane of the hard vinyl chloride corrugated sheet25' of the propulsion double pipe 11' is capped with a blowingpolystyrene member 26 (not illustrated) for cut-off of water, it may beavoided, when the cement milk is filled to the connected portion of thedouble walled pipe 11 and 11', that the cement milk intrudes into thegap between the hard vinyl chloride corrugated sheet 25 and the outerpipe 13, and the gap between the hard vinyl chloride corrugated sheet 25and the polypropylene tube 17. Hence, it does not happen that the hardvinyl chloride corrugated sheet 25 is fixed by the cement milk.Consequently, the flexibility of the hard vinyl chloride corrugatedsheet 25 is ensured. Thus, in a case where a misalignment or the likebetween the outer pipes 13 and 13' exists, the positioning isfacilitated and its working efficiency is remarkably enhanced.

In the next step, as shown in FIG. 13(E), a push wheel 31 is fitted tothe rear end of the double walled pipe 11 so as to couple with only therear end plane 13c of the outer pipe 13, a propulsion oil jack 33 is setto push the push wheel 31, and the double walled pipe 11 is propelledunderground, upon acting on the outer pipe 13 with the thrust, togetherwith the double walled pipe 11' and the further preceding double walledpipes.

In order to avoid such a situation that the cement milk intrudes intothe gap between the hard vinyl chloride corrugated sheet 25' and theouter pipe 13', and the gap between the hard vinyl chloride corrugatedsheet 25' and the polypropylene tube 17', so that an amount of cementmilk to be filled to the connected portion is increased, it ispreferable to cap with the styrene foam not only the front end plane ofthe hard vinyl chloride corrugated sheet, but also the back end planethereof.

While FIGS. 13(A)-13(E) show a jacking method in which a jacking iscarried out after cement milk is flowed into the connected portion oftwo double walled pipes 11 and 11', it is acceptable, also in thisexample provided with the corrugated sheet, to adopt the jacking methodshown in FIGS. 8(A)-8(F) in which after a multiple double walled pipesare propelled, the connected portions are subjected to the groutdisposal. In this case, from the view point that a flexibility of thecorrugated sheet is maintained, there is no need to mount a cap forcut-off of water.

FIG. 14 is a sectional side elevation of a double walled pipe accordingto the fourth embodiment of the present invention, extending along thelongitudinal direction. FIG. 15 is a sectional view of the double walledpipe shown in FIG. 14 looking from the right side of FIG. 14. FIG. 16 isan enlarged sectional side elevation of a portion circled by a dashedline D shown in FIG. 14. Here also, there will be explained, by way ofexample, a double walled steel pipe for gas.

FIG. 14 shows a preceding double walled pipe 51' which has beenpropelled underground and of which only a part of the rear end isprojected into a shaft, and a subsequent double walled pipe 51 which isto be coupled to the rear end of the preceding double walled pipe 51'and to be propelled underground together with the double walled pipe51'. These double walled pipes 51 and 51' each have the same structure.

The double walled pipe 51 comprises an inner pipe 52 constructed of asteel pipe having about 900 mmφ, an outer pipe 53 also constructed of asteel pipe having about 1200 mmφ, and two ring members 54 which aredisposed at two portions between the inner pipe 52 and the outer pipe53. Each of the ring member 54 is provided with a grout hose insertionopening 54c (refer to FIG. 17). A grout hose 56 is inserted into thegrout hose insertion opening 54c.

Further, at the upper and lower and the right and left near the middleor its vicinity of the outer pipe 53, and at the upper and lower and theright and left near the rear end portion or its vicinity of the outerpipe 53 regarding the jacking direction, there are provided check valves59, respectively, each serving to open when pushed from the inside ofthe pipe and to close when pushed from the outside of the pipe. Thefront end portion of the outer pipe 53 is provided with a guide ring 60as a guide member, as seen from FIG. 16. As will be described later indetail, when the outer pipe 53 of the double walled pipe 51 is forwardlyslid on the ring member 54, the guide ring 60 enters the inside of anouter pipe 53' of the double walled pipe 51' through a back end plane53c' thereof. In addition, a front end plane 53b of the outer pipe 53 ofthe double walled pipe 51 is coupled to the back end plane 53c' of theouter pipe 53' of the double walled pipe 51'. In this manner, theprovision of the guide ring 60 makes it possible to reliably couple theouter pipes 53 and 53' to each other, even if the misalignment exists alittle between the outer pipes 53 and 53', since an error is absorbed.

An outside face of the inner pipe 52 is covered with a polyethylenemember 57. As shown in FIG. 14, after a front end plane of the innerpipe 52 of the double walled pipe 51 and a back end plane of the innerpipe 52' of the double walled pipe 51' are coupled to each other, theseinner pipes are welded at their coupled portion. After the welding, theportion undergone the welding is covered with a anticorrosionpolyethylene tube.

FIG. 17 is a perspective view of part of a ring member. FIGS. 18(A) and(B) are a sectional side elevation of part of the ring member and afront view of part of the ring member. FIG. 19 is a partially enlargedview of a ring member as a constituent part of the double walled pipeshown in FIG. 14. It is noted that FIG. 17 and FIGS. 18(A)and (B) omit arubber disc 63 shown in FIG. 19 for the purpose of avoiding thecomplexity.

The ring member 54 comprises a cylindrical base plate 54a holding theinner pipe 52 and a rib 54b rising from the base plate 54a. The ringmember 54 is constructed of two pieces of half ring for convenience of amounting. These two pieces of half ring surround the periphery of theinner pipe 52 and are bolted so that the ring member 54 is fixed on theinner pipe 52. The outer wall of the inner pipe 52 is covered with thepolyethylene member 57 as mentioned above. The inner wall of the ringmember 54 is equipped with a rubber plate 61 so as not to damage thepolyethylene member 57 when the ring member 54 is fixed. The rubberplate 61 is also put into the portion of two pieces of half ring of thering member 54 to be bolted. The rib 54b of the ring member 54 isequipped with a grout hose insertion hole or aperture 54c.

The ring member 54 is arranged, as shown in FIG. 19, in such a mannerthat the rubber plate 63 is fastened on the rib 54b and the inner wallof the outer pipe 53 directly contacts with the rubber disc 63. Therubber disc 63 is used for the purpose of avoiding such a situation thatin a case where the inner pipe 52 and the outer pipe 53 are arranged ona concentric circle basis, which will be described later, when a spacebetween the inner pipe 52 and the outer pipe 53 is filled with cementmilk, the filling cement milk is leaked in excess over space partitionedby two pieces of the ring member 54 into the neighboring spaces. In thiscase, it is sufficient that only the space of the coupled portion of thetwo double walled pipes 51 and 51' is filled and in addition a backfilling is simply conducted, and there is no need to fill the spacesandwiched between two pieces of the ring member 54 included in a singledouble walled pipe 51. In a case where the inner pipe 52 and the outerpipe 53 are not arranged on a concentric circle basis, however, the ringmember 54 does not serve to prevent the cement milk from flowing intothe neighboring spaces over the space partitioned by the ring members54. Consequently, in this case, even if it is intended to fill withcement milk only the coupled portion of two double walled pipes, thecement milk will flow through a space of the ring members 54 into theneighboring spaces. As a result, the cement milk is filled over thespace sandwiched between the inner pipe 52 and the outer pipe 53 in itsentirety, and in addition the back filling is conducted. The outer pipe53 is supported by only the rubber disc 63 in the inner wall, so thatthe outer pipe 53 may reliably and readily slide relative to the innerpipe 52 and the ring members 54.

FIGS. 20(A)-20(F) are typical illustrations useful for explanation of ajacking execution procedure of burying underground the double walledpipe having the structure shown in FIGS. 14 to 19.

As shown in FIG. 20(A), assume that the preceding double walled pipe 51'has been propelled underground in accordance with a jacking method and apart of the rear end thereof is projected into a shaft. The subsequentdouble walled pipe 51 is prepared in connection with the precedingdouble walled pipe 51' of which a part of the rear end is projected intothe shaft, and is disposed in such a manner that the front end plane 52bof the inner pipe 52 of the double walled pipe 51 and the back end plane52c' of the inner pipe 52' of the double walled pipe 51' are coupled toeach other (refer to FIG. 14).

In the next step, as shown in FIG. 20(B), the front end plane 52b of theinner pipe 52 of the double walled pipe 51 and the back end plane 52c'of the inner pipe 52' of the double walled pipe 51', which are coupledto each other, are welded. The state after the welding is inspected by aX ray. When passing inspection, the portion undergone the welding iscovered with a polyethylene tube 70. Incidentally, as aforementioned,the outside face of the inner pipe 52, also including portions otherthan the portion undergone the welding, is covered with the polyethylenemember 57.

In the next step, as shown in FIG. 20(C), the grout hoses 56 of thedouble walled pipe 51 and the double walled pipe 51' are connected toeach other. Incidentally, with respect to a pair of grout hoses whichwill be finally located at the middle or its vicinity when a multipleconnection of the grout is completed through the pipe jacking, they areleft not to be connected so that the connected grout hoses can beseparately drawn half-and-half at the front and rear in a jackingdirection, respectively.

Thereafter, the outer pipe 53 is slid forwardly relative to the innerpipe 52 and the ring member 54 until it takes a state shown in FIG.20(D) from the state shown in FIG. 20(C), so that the front end plane53b of the outer pipe 53 is coupled to the back end plane 53c' of theouter pipe 53'.

In the next step, as shown in FIG. 20(E), a push wheel 71 is fitted tothe rear end of the double walled pipe 51 so as to couple with only therear end plane 53c, a propulsion oil jack 72 is set to push the pushwheel 71, and the double walled pipe 51 is propelled underground, uponacting on the outer pipe 53 with the thrust, together with the doublewalled pipe 51' and the further preceding double walled pipes. The frontend portion of the first stage of double walled pipe is mounted with anexcavation head (not illustrated), thereby propelling while digging. Itis acceptable that setting of the push wheel 71 and the propulsion oiljack 72 is conducted prior to sliding of the outer pipe 53, and theouter pipe 53 is slid by the propulsion oil jack 72.

After a series of processes as mentioned above is repeatedly applied fora number of double walled pipes, the cement milk is flowed into thegrout hose 56 (refer to FIG. 15) so as to fill a space between the ringmember-to-ring member and a space partitioned by outside face of theinner pipe 52 and the inner wall of the outer pipe 53, while the grouthose is sequentially drawn in such a manner that the top of the grouthose is sequentially disposed between the ring member-to-ring member ofthe multiple connection of double walled pipes. In this case, when thegrout hose 56 is drawn backwards in the pipe jacking direction, in orderto prevent the cement milk from overflowing through the grout hoseinsertion opening 54c (refer to FIG. 17) of the forward ring member ofthe preceding double walled pipes, it is preferable to close the opening54c. When the respective spaces are filled with the cement milk, water,earth and sand, etc., which creep between the inner pipe 52 and theouter pipe 53, are exhausted by the cement milk out of the outer pipe 53via the check valve 59, and in addition the cement milk itself alsoflows out via the check valve 59, whereby the outside face of the outerpipe 53 is also covered with the cement milk, as shown in FIG. 20(F).Thus, it is possible to provide the underground pipe with greatertoughness, and in addition to prevent a settlement of the ground level.

According to the present embodiment, while the grout hose 56 has beeninserted into the opening 54c provided on the ring member 54, thepresent invention does not exclude an insertion of the grout hose itselfbefore filling the cement milk after the pipe jacking. In such a case,the opening 54c of the ring member 54 is beforehand equipped with a tubehaving a cement milk flow aperture, and in step shown in FIG. 20 (C)these tubes are connected, and after completion of the pipe jacking thegrout hose is inserted into the tube.

FIG. 21 is a sectional side elevation of a double walled pipe accordingto the fifth embodiment of the present invention, extending along thelongitudinal direction.

FIG. 22 is a sectional view taken along the line E--E of FIG. 21. FIG.23 is an enlarged sectional side elevation of a portion circled by adashed line F of FIG. 21.

FIG. 21 shows a preceding double walled pipe 81' which has beenpropelled underground and of which only a part of the rear end isprojected into a shaft, and a subsequent double walled pipe 81 which isto be coupled to the rear end of the preceding double walled pipe 81'and to be propelled underground together with the double walled pipe81'. These propulsion double pipes 81 and 81' each have the samestructure.

The double walled pipe 81 comprises an outer pipe 82 and an inner pipe83 disposed inside of the outer pipe 82. The inner pipe 83 is disposedinside of the outer pipe 82 vis a supporting leg 83d which is fixed onthe inner pipe 83.

An outer pipe 82' is equipped with a first check valve 85' near the rearend of the outer pipe 82' with respect to the pipe jacking direction.The first check valve 85' permits an one-way flow of a back fillingmaterial from the inside of the outer pipe 82' to the outside thereof.Coupled to the first check valve 85' is one end of a first back fillingtube 87' extending backwards (right side in FIG. 21) with respect to thepipe jacking direction.

An insertion joint 92 is mounted at the front end of the outer pipe 82.The insertion joint 92 is operative, when the outer pipe 82 of thedouble walled pipe 81 is propelled and the front end of the the outerpipe 82 is connected to the rear end of outer pipe 82' of the doublewalled pipe 81', to enter inside of the outer pipe 82' of the doublewalled pipe 81'. In this manner, the provision of the insertion joint 92makes it possible to reliably couple the outer pipes 82 and 82' to eachother, even if the misalignment exists a little between the outer pipes82 and 82', since an error is absorbed.

At the periphery of the inner pipe 83, there is provided a filling tube84 through which concrete passes to fill a space between the outer pipe82 and the inner pipe 83. The filling tube 84 is fixed on a fixing base93, and is equipped with a second check valve 86 near the front end ofthe filling tube 84 with respect to the pipe jacking direction. Thesecond check valve 86 permits an one-way flow of the back fillingmaterial from the inside of the filling tube 84 to the outside thereof.Coupled to the second check valve 86 is one end of a second back fillingtube 89 extending forwards (left side in FIG. 21) with respect to thepipe jacking direction.

As shown in FIG. 21, after a back end plane 83b' of the inner pipe 83'of the preceding double walled pipe 81' and a front end plane 83a of theinner pipe 83 of the double walled pipe 81 are coupled to each other,the front end plane 83a of the inner pipe 83 and the back end plane 83b'of the inner pipe 83' are welded at their coupled portion. After thewelding, as shown in FIG. 23, the filling tube 84' of double walled pipe81' and the filling tube 84 of the double walled pipe 81 are connectedeach other through a coupling tube 91 both ends of which are fixed onthe filling tubes 84 and 84' by ring members 95 and 95', respectively.Further, the first back filling tube 87' of the double walled pipe 81'and a second back filling tube 89 of the double walled pipe 81 areconnected through a flexible pipe 88 both ends of which are clamped onthe first back filling tube 87' and a second back filling tube 89 byclamped bands 94' and 94, respectively.

FIG. 21 shows a state that the inner pipes 83 and 83' are welded, thefilling tubes 84 and 84' are connected, and the back filling tubes 89and 87' have been connected. After the state shown in FIG. 21, the outerpipe 82 of the double walled pipe 81 is propelled to move in the pipejacking direction (left in FIG. 21), so that the insertion joint 92mounted on the tip of the outer pipe 82 slides inside of the rear end ofthe outer pipe 82' of the propulsion double pipe 81', whereby the doublewalled pipes 81 and 81' are reliably coupled to each other. In thecoupling, the sliding occurs between the supporting leg 83d and theinside of the outer pipe 82. After the coupling, the outer pipe 82 ofthe double walled pipe 81 is further propelled so that the double walledpipes 81 and 81' are propelled under the ground. Even if there occursduring the pipe jacking a relative rotation between the outer pipes 82,82' and the inner pipes 83, 83', it does not happen that the first backfilling tube 87' and the second back filling tubes 89 are damaged orbroken, since the flexible pipe 88, which connects the first backfilling tube 87' and the second back filling tubes 89 each other, has aflexibility. Further, since the double walled pipes 81 and 81' areequipped with the first check valves 85 and 85', respectively, it ispossible to avoid such a situation that earth and sand or the like creptin the back filling tubes during the pipe jacking. After the pipejacking, a series of processes as mentioned above is repeatedly appliedfor a plurality of double walled pipes.

Inside of the filling tubes 84 and 84', there is provided a hose (notillustrated) adapted to flow concrete for a back filling of theperiphery of the outer pipes 82 and 82'. The hose is connected to aso-called double packer (not illustrated) which is located inside of thefilling tube 84 of the double walled pipe 81 at the front end thereof.The double packer serves to exhaust the back filling concrete out of theouter pipes 82 and 82' via the second check valve 86, the back fillingtube, and first check valve 85 or 85'. After the back filling process,there will still remain the concrete inside of the back filling tube.However, the second check valve 86 prevents the the remaining concretefrom returning into the filling tubes 84 and 84'. Thus, it may beavoided that the inside of the filling tubes 84 and 84' is stopped upwith the concrete used for back filling. Consequently, after the backfilling, it is possible to flow through the filling tubes 84 and 84' amiddle filling concrete for filling a space between the outer pipes 82,82' and the inner pipes 83, 83'. Further, even if there occurs duringthe middle filling a relative rotation between the outer pipes 82, 82'and the inner pipes 83, 83', it does not happen that the back fillingtubes are damaged or broken, since the flexible pipe 88 has aflexibility.

Incidentally, according to the present embodiment, the inner pipe 83 issimply disposed inside of the outer pipe 82. The present invention isnot restricted to an application for only a case where the inner pipe 83is simply disposed inside of the outer pipe 82, and does not excludeother applications, for example, to a double walled pipe 81 and the likewhich is equipped with such an arrangement that a predeterminedintermediate member is provided between the inner pipe 83 and the outerpipe 82, so that a relative positioning between the inner pipe 83 andthe outer pipe 82 is conducted by the intermediate member, and the innerpipe 83 and the outer pipe 82 may be relatively slid.

FIG. 24 is a sectional side elevation of a double walled pipe accordingto the sixth embodiment of the present invention, extending along thelongitudinal direction. FIG. 25 is a partially enlarged view of firstcheck valves 85a˜85c' as constituent parts of the double walled pipeshown in FIG. 24. In these figures, the same parts are denoted by thesame reference numbers as those in FIGS. 21, 22 and 23 involved in thefifth embodiment, and the redundant description will be omitted.

The outer pipe 82' shown in FIG. 24 is equipped with five pieces offirst check valve 85a'-85e' which are disposed in series in alongitudinal direction. Of these five pieces of first check valve85a'-85e', the first check valve 85a' is connected through a socketjoint 98 and an elbow joint 97 to the first back filling tube 87'. Theremaining other first check valves 85b'-85e' each are connected througha socket joint 98 and a T-piece 99 to the first back filling tube 87'.

The five pieces of first check valve 85a'-85e' shown in FIG. 24 each aremounted at an adequate point of the outer pipe 82' in accordance with asoil condition of an area where the double walled pipe 81' is to beburied, so that concrete for back filling may be effectively sent outfrom these first check valve 85a'85e'. Thus, it is possible to expect aneffect of the back filling, for example, an enhancement of a reliabilityof the reinforcement of the double walled pipes.

FIG. 26 is a sectional side elevation of a double walled pipe accordingto the seventh embodiment of the present invention, extending along thelongitudinal direction. FIG. 27 is a sectional view taken along the lineG--G of FIG. 26.

FIG. 26 shows a preceding double walled pipe 101' which has beenpropelled underground and of which only a part of the rear end isprojected into a shaft, and a subsequent double walled pipe 101 which isto be coupled to the rear end of the the preceding double walled pipe101' and to be propelled underground together with the double walledpipe 101'. These double walled pipes 101 and 101' each have the samestructure.

The double walled pipe 101 comprises an outer pipe 102, an inner pipe103 disposed inside of the outer pipe 102, and two pieces of rib band105 surrounding the periphery of the inner pipe 103. The two pieces ofrib band 105 each are provided with two elliptic holes 105d (refer toFIG. 27) through which an auxiliary pipe arrangement 104 is slidinglyinserted. The auxiliary pipe arrangement 104 is provided with a malescrew at an outer wall of the tip 104a thereof with respect to thepropellent direction (left FIG. 26) and a female screw at an inner wallof the rear end 104b thereof with respect to the propellent direction.

The outer pipe 102 is provided with an insertion joint 108 at the topthereof with respect to the pipe jacking direction. The insertion joint108 is operative, when the outer pipe 102 of the double walled pipe 101is propelled and the front end of the outer pipe 102 is connected to therear end of outer pipe 102' of the double walled pipe 101', to creptinside of the outer pipe 102' of the double walled pipe 101'. In thismanner, the provision of the insertion joint 108 makes it possible toreliably couple the outer pipes 102 and 102' to each other, even if themisalignment exists a little between the outer pipes 102 and 102', sincean error is absorbed.

As shown in FIG. 27, the rib band 105 comprises an upper rib band 105aand a lower rib band 105c. These upper rib band 105a and lower rib band105c are urged each other by a bolt 106 so that the rib band 105 isfixed to the inner pipe 103. The upper rib band 105a is equipped withtwo elliptic holes 105d at its upper part. These elliptic holes 105dextend in a peripheral direction of the inner pipe 103. The auxiliarypipe arrangement 104 is slidingly inserted into the right side ofelliptic hole 105d. The lower rib band 105c is equipped with twosupporting legs 105b at its lower part. The inner pipe 103 is disposedinside of the outer pipe 102 through the supporting legs 105b.

FIG. 26 shows a state that the rear end 103b' of the inner pipe 103' ofthe double walled pipe 101' and the front end 103a of the inner pipe 103of the double walled pipe 101 are coupled each other and has beenwelded.

FIG. 28 is an enlarged sectional side elevation of a portion circled bya dashed line H of FIG. 26, in a state that auxiliary pipe arrangementsare slid in the pipe jacking direction and directly coupled together.

The auxiliary pipe arrangement 104 of the double walled pipe 101 is slidin the pipe jacking direction shown by the arrow from a state as shownin FIG. 26 so that the tip of the auxiliary pipe arrangement 104 iscoupled to the rear end 104b' of the auxiliary pipe arrangement 104' ofthe double walled pipe 101'. It happens that there occurs during thepipe jacking a relative rotation between the inner pipe 103' of thepreceding double walled pipe 101' and the outer pipe 102' thereof.However, even if the misalignment exists a little between the auxiliarypipe arrangements 104 and 104', it is possible to reliably position theauxiliary pipe arrangements 104 and 104', since the auxiliary pipearrangement 104 is inserted into the elliptic hole 105d extending in aperipheral direction of the inner pipe 103. Thus, the auxiliary pipearrangements 104 and 104' may be readily connected by means of, forexample, screw-operating the male screw of the rid 104a of the auxiliarypipe arrangement 104 and the female screw of the rear end 104b' of theauxiliary pipe arrangement 104'. As another fashion, it is acceptable toconnect the auxiliary pipe arrangements 104 and 104' through a nipple(not illustrated).

After the auxiliary pipe arrangements 104 and 104' are connected, theouter pipe 102 of the double walled pipe 101 is propelled so that theinsertion joint 108 of the front end of the outer pipe 102 with respectto the pipe jacking direction crepts inside of the outer pipe 102' ofthe double walled pipe 101', whereby the outer pipes 102 and 102' arereliably connected together. After the connection, the outer pipe 102 isfurther propelled so that the double walled pipe 101 is propelledunderground. After the pipe jacking, a series of processes as describedabove is repeatedly conducted, so that a plurality of double walledpipes 101 are sequentially pushed.

A space between the inner pipe 103 and outer pipe 102 of the pluralityof double walled pipes 101 after the pipe jacking is filled withconcrete or the like through one end (not illustrated) of the auxiliarypipe arrangements 104, so that the inner pipe 103 and outer pipe 102 arefixed. According to this arrangement, since the auxiliary pipearrangements 104 are directly coupled together, it is possible to expecta satisfactory passage of the concrete through the space including theconnected portion of the auxiliary pipe arrangements 104 even theconcrete passes through the auxiliary pipe arrangements 104 upon thefilling.

Incidentally, according to the present embodiment, the inner pipe 103 issimply disposed inside of the outer pipe 102. The present invention isnot restricted to an application for only a case where the inner pipe103 is simply disposed inside of the outer pipe 102, and does notexclude other applications, for example, to a double walled pipe and thelike which is equipped with such an arrangement that a predeterminedintermediate member is provided between the inner pipe 103 and the outerpipe 102, so that a relative positioning between the inner pipe 103 andthe outer pipe 102 is conducted by the intercalary member, and the innerpipe 103 and the outer pipe 102 may be relatively slid.

Further, according to the present embodiment, while the auxiliary pipearrangements are explained in the form of a so-called middle fillingtube, the auxiliary pipe arrangements in the present invention is notrestricted in the use, and does not excludes other use, for example, itis acceptable to be used as a back filling tube for covering the outsideof the outer pipe with concrete or the like, or a tube for passing along object, such as a rope and a cable, according to the necessity.

FIG. 29 is a sectional side elevation of a double walled pipe accordingto the eighth embodiment of the present invention, extending along thelongitudinal direction.

FIG. 30 is a sectional view taken along the line I--I of FIG. 29. FIG.31 is an enlarged sectional side elevation of a portion circled by adashed line J of FIG. 29.

FIG. 29 shows a preceding double walled pipe 111' which has beenpropelled underground and of which only a part of the rear end isprojected into a shaft, and a subsequent propulsion double pipe 111which is to be coupled to the rear end of the preceding double walledpipe 111' and to be propelled underground together with the doublewalled pipe 111'. These double walled pipes 111 and 111' each have thesame structure.

The double walled pipe 111 comprises an outer pipe 112, an inner pipe113 disposed inside of the outer pipe 112, and two pieces of rib band115 surrounding the periphery of the inner pipe 113. As shown in FIG.30, the rib band 115 comprises an upper rib band 115a and a lower ribband 115c. These upper rib band 115a and lower rib band 115c are securedeach other by a bolt 116 so that the rib band 115 is fixed to the innerpipe 113. The upper rib band 115a is equipped with two elliptic holes115d at its upper part. These elliptic holes 115d extend in a peripheraldirection of the inner pipe 113, and penetrate in the longitudinaldirection of the inner pipe 113. Inserted into the the right side ofelliptic hole 115d is an auxiliary pipe arrangement 114 adapted forpassing concrete to fill a space between the outer pipe 112 and innerpipe 113. The lower rib band 115c is equipped with two supporting legs115b at its lower part. The inner pipe 113 is disposed inside of theouter pipe 112 through the supporting legs 115b.

The outer pipe 112 is provided with a ring member 118 at the tip thereofwith respect to the pipe jacking direction (left side in FIG. 29). Thering member 118 is disposed in such a way that one end of the ringmember is inserted from a tip of the outer pipe 112 into the insidethereof to be fixed on an inside face thereof and the another end isprojected from the tip of the outer pipe 112. The projected portion ofthe ring member 118 is formed, as shown in FIG. 31, with a flat section118c having a surface aligning with the inside face of the outer pipe112, and a taper section 118b inclined left downwards from the flatsection 118c. The flat section 118c is equipped with a groove or channel118a surrounding the periphery of the ring member 118. A rubber ring 119is engaged with the channel 118a.

FIG. 29 shows a state that the rear end 113b' of the inner pipe 113' ofthe double walled pipe 111' and the front end 113a of the inner pipe 113of the double walled pipe 111 are coupled each other and has beenwelded. Thereafter, the auxiliary pipe arrangement 114' of the doublewalled pipe 111' and the auxiliary pipe arrangement 114 of the doublewalled pipe 111 are connected each other.

The rear end plane 113b' of the inner pipe 113 and the front end plane113a of the inner pipe 113 are welded. The state after the welding isinspected by a X ray. When a welding failure is found on the weldedportion, the welding material of the failure portion is subjected togousing and the same portion is again welded. Thereafter, the inspectionis again conducted on the re-welded portion. If the welding failure isfound again on the re-welded portion, the inner pipes 113' and 113 arecut off by a certain length with the welded portion in the center, sincethere is a possibility that a heating for welding twice over affords theinner pipes 113' and 113 on the vicinity of the portion undergone thewelding a variation in mechanical characters. Now, the rear end plane113b' of the cutting inner pipe 113' and the front end plane 113a of thecutting inner pipe 113 are welded. Incidentally, according to the sortof tubes, it is acceptable not to cut off the welded portion of theinner pipes when the failure for the second takes place, but to cut offthe welded portion of the inner pipes when the failure for apredetermined number of times such as third time or more takes place.

In this manner, if the inner pipes 113' and 113 are partially cut off,the outer pipes 112' and 112 will become longer than the inner pipes113' and 113, respectively. Hence, it is necessary for the outer pipes112' and 112 to be cut off by the corresponding length of the cut offparts of the inner pipes 113' and 113, respectively.

To cut off the outer pipes 112' or 112, there are considered, as a cutoff point thereof, three points such as the rear end of the outer pipe112' of the preceding double walled pipe 111', the front end of theouter pipe 112 of the subsequent double walled pipe 111, or the rear endof the outer pipe 112 of the subsequent double walled pipe 111. If therear end of the outer pipe 112' is cut off, this involves such a dangerthat the inner pipe 113' is damaged due to the heat or the likegenerating at the time of cutting off. It is similar also in a casewhere the front end of the outer pipe 112 is cut off. In this case,since the ring member 118 must be again mounted on the tip of the cutpart, it will take much time. Whereas, if the rear end of the outer pipe112 is cut off, this involves no danger such that the inner pipe 113 isdamaged, since there is no inner pipe at the rear end of the outer pipe112. In view of the foregoing, it is preferable to cut off the rear endof the outer pipe 112.

FIG. 32 is a view showing a state that a ring member 118 has beeninserted into the rear end of the outer pipe 112' of the front in a pipejacking direction upon jacking of the outer pipe 112.

At the top, with respect to the pipe jacking direction, of the outerpipe 112 of the double walled pipes 111, there is provided the ringmember 118. A major diameter of the taper section 118b of the ringmember 118 is smaller than that of the inner periphery of the outer pipe112'. Consequently, as the outer pipe 112 is propelled, the ring member118 is readily inserted into the inside of the outer pipe 112'. Hence,it is possible to reliably couple the outer pipes 112 and 112' to eachother, even if a misalignment exists a little between the outer pipes112 and 112'. Further, since the rubber ring 119 of the ring member 118is placed in contact with the inside face of the outer pipe 112' incondition that the ring member 118 is inserted into inside of the outerpipe 112', the coupling portion of the outer pipes 112 and 112' issealed by the rubber ring 119.

After the state shown in FIG. 32, the double walled pipe 111 ispropelled underground, upon acting on the outer pipe 112 with thefurther thrust. After the pipe jacking, the similar process as mentionedabove is repeatedly performed so that a plurality of double walled pipes111 are sequentially propelled. A space between the inner pipe 113 andthe outer pipe 112 of the double walled pipe 111 after the pipe jackingis filled with concrete or the like through one end (not illustrated) ofthe auxiliary pipe arrangement 114, so that the inner pipe 113 and theouter pipe 112 are fixed together. Since the rubber ring 119 seals theconnected section of the outer pipe-to-outer pipe, it does not happenthat ground water or the like intrudes into the space between the innerpipe 113 and the outer pipe 112 through such a connected section.Therefore, the space between the inner pipe 113 and the outer pipe 112may be filled up with concrete or the like. Incidentally, it isconsidered that after the double walled pipes 111 are buried, a qualityof the rubber ring 119 is deteriorated, as a result, a sealing of thecouped section of the outer pipe-to-outer pipe becomes insufficient. Insuch a case, however, this involves no problem, since the concretefilled between the inner pipe 113 and the outer pipe 112 has beenalready harden.

According to the present embodiment, while there is provided the channel118a only one piece on the flat section 118c of the ring member 118, thepresent invention does not exclude the use of a plurality of channels toensure a sealing of a space between the inner periphery of the outerpipe and the ring member with greater reliability.

Incidentally, according to the present embodiment, the inner pipe 113 issimply disposed inside of the outer pipe 112. The present invention isnot restricted to an application for only a case where the inner pipe113 is simply disposed inside of the outer pipe 112, and does notexclude other applications, for example, to a double walled pipe and thelike which is equipped with such an arrangement that a predeterminedintermediate member is provided between the inner pipe 113 and the outerpipe 112, so that a relative positioning between the inner pipe 113 andthe outer pipe 112 is conducted by the intermediate member.

FIG. 33 is a view useful for understanding a pipe end structure of aleading pipe according to an embodiment of the present invention.

A double walled pipe 121 has been propelled underground through a shaft120 toward left in the figure, using a jacking apparatus (notillustrated). To propel the double walled pipes, there is constructed abearing wall (not illustrated) on a side wall located over against aside wall 120a. The double walled pipe 121 is pushed by the jackingapparatus until a rear end of the double walled pipe 121 is keptprojecting into the shaft 120, as shown in FIG. 33, while causing thebearing wall to bear a reaction force of the jacking. In pipe jacking,in order to avoid such a situation that an inner pipe 122 is damaged,the double walled pipe 121 is propelled upon acting on only the rear endof an outer pipe 123 with the thrust. After completion of the pipejacking, the rear end of the inner pipe 122 of the double walled pipe121 is capped with a protection cap 125. Further, the rear end of thedouble walled pipe 121 is capped with a protection tube 126 at adistance from the protection cap 125. After capping of the protectiontube 126, a bearing wall 127 is constructed in such a manner thatconcrete is slashed so as to cover the rear end of the double walledpipe 121 and the protection tube 126 and in addition to contact with theside wall 120a.

While the double walled pipe (not illustrated) is propelled undergroundfrom the side wall located over against the side wall 120a while causingthe bearing wall 127 to bear a reaction force of the jacking apparatus(not illustrated), in such a case, after a bearing wall (notillustrated), which is constructed on the side wall located over againstthe side wall 120a, is demolished, the double walled pipe is propelledunderground from the side wall located over against the side wall 120a.In pipe jacking, in order to prevent the reaction force acting on thebearing wall 127 from applying to the inner pipe 122, the protectiontube 126 is capped so as not to contact with the inner pipe 122 at therear end of the double walled pipe 121. After completion of thepropulsion of the double walled pipe, the bearing wall 127 is demolishedand the protection tube 126 is taken off from the rear end of the doublewalled pipe 121, and in addition the protection cap 125 is taken offfrom the rear end of the inner pipe 122. After these parts are takenoff, the double walled pipe 121 shown in FIG. 33 and a double walledpipe propelled from the side wall over against the side wall 120a areconnected to each other. In pipe jacking of the double walled pipe, therear end of the double walled pipe 121 is protected by the protectiontube 126. Thus, it is possible to avoid such situations that concrete isadhered on the rear end of the double walled pipe, or water intrudesthereinto. Therefore, it is possible to readily perform the connectionof double walled pipe-to-double walled pipe.

In a jacking method for the double walled pipes according to the presentembodiment, only a change of the pipe jacking direction of a excavationdevice (not illustrated), which is set up on a concrete floor 128,permits the double walled pipes to propel in two directions. Thisfeature makes it possible to reduce the cost and the term of works aswell. Further, a jacking method according to the present embodimentpermits the number of shafts used as only a carry-over shaft but notused as a pipe jacking shaft to be increased. This feature makes itpossible to reduce a working amount for preparing the shafts.

When the bearing wall 127 is demolished and the protection tube 126 istaken off from the rear end of the propulsion double pipe 121, accordingto the present embodiment, it is possible to readily take off theprotection tube 126, since the insertion joint 126a is simply insertedinside of the rear end of the double walled pipe 121.

Further, according to the present embodiment, the protection tube 126 iscapped on the rear end of the double walled pipe so as not to contactwith the inner pipe 122. This feature makes it possible to prevent theinner pipe 122 from being damaged owing to the reaction force of thejacking of the double walled pipes.

Furthermore, while the protection cap 125 is necessarily needed, it ispreferable that the protection cap 125 is capped on the rear end of theinner pipe 122, since the protection cap 125 serves to reliably preventearth and sand or water, etc. from intruding into the inside of theinner pipe 122.

The bearing wall 127 is supported by the side wall 120a and the doublewalled pipe 121 as well. Thus, it is possible to sufficiently bear thereaction force acting on the jacking apparatus.

FIG. 34 is a view useful for understanding a pipe end structure of aleading pipe according to an embodiment of the present invention.

A dummy pipe 131, constituting the leading pipe, is propelled from itsfront end in the pipe jacking direction (left side in FIG. 34) through aside wall of a shaft 130 under the ground. An inner wall of the rear endof an adapter tube 134 is welded with an insertion joint 134a,projecting from the rear end, in the peripheral direction. An inner wallof the adapter tube 134 is welded with a reinforcing ring 134b forpreventing a buckling of the adapter tube 134, in the peripheraldirection. A rear end of the dummy pipe 131 of which the front end hasbeen propelled underground is welded with the adapter tube 134 mentionedabove. An outer pipe 143a is propelled by a jacking apparatus (notillustrated) in such a manner that the insertion joint 134a of theadapter tube 134 enters the inside of the outer pipe 143a, so that afront end of the outer pipe 143a couples with the rear end of theadapter tube 134. A rubber plate 134c is fixed on the right side (inFIG. 34) of the reinforcing ring 134b. The front end of the inner pipe142 is in contact with the reinforcing ring 134b via the rubber plate134c. The outer pipe 143a and an inner pipe 142, constituting apropulsion double pipe 141, are relatively slidingly movable. Betweenthe outer pipe 143a and the inner pipe 142, there is provided a grouttube 144 used for filling with concrete (not illustrated) a spacebetween the outer pipe 143a and the inner pipe 142. The inside of thedummy pipe 131 is equipped with cabin units, a television camera, and anindicator, etc. (not illustrated). An excavation disposed on the frontend of the dummy pipe 131 is equipped with a crusher head, a shield mainbody, a direction control jack, and a laser reflector, etc. (notillustrated).

The adapter 134 is welded with the rear end of the dummy pipe 131, afterthe dummy pipe 131 is propelled underground as shown in FIG. 34. Weldingof the end planes of these parts is readily conducted from theirexterior. Thus, it is possible to implement the welding in short time.The insertion joint 134a of the adapter tube 134 is inserted inside ofthe outer pipe 143a, so that the insertion joint 134a serves to performa positioning of the outer pipe 143a. The reinforcing ring 134b of theadapter tube 134 is in contact with a tip of the inner pipe 142 via therubber plate 134c, so that the reinforcing ring 134b serves to perform apositioning of the inner pipe 142. Hence, it is avoided such a situationthat the reinforcing ring 134b enters the inside of the dummy pipe 131.The use of the rubber plate 134c prevent an occurrence of damage on theinner pipe 142 due to the direct contact of the inner pipe 142 and thereinforcing ring 134b together.

After the double walled pipe 141 arrives at other shaft (notillustrated) located at regular intervals from the shaft 130, the dummypipe 131 and the adapter tube 134, constituting the leading pipe, aretaken off from the double walled pipe 141. When the dummy pipe 131 andthe adapter tube 134 are taken off from the double walled pipe 141,according to the present embodiment, it is possible to readily take offthe leading pipe from the double walled pipe 141, since the insertionjoint 134a of the adapter tube 134 is simply inserted into the outerpipe 143a.

While the reinforcing ring 134b is provided, as described above, forpreventing a buckling of the adapter tube 134, the reinforcing ring 134bserves also to perform a positioning of the inner pipe 142. Therefore,according to the present embodiment, the reinforcing ring 134b isadapted to serve as a stopper for positioning the inner pipe 142. Whilethe reinforcing ring 134b is fixed to the adapter tube 134 extendingover overall circumference thereof, from the view point that it servesas only the stopper, it is sufficient for the stopper to be fixed to theadapter tube 134 extending over partial extent which permits positioningof the inner pipe 142.

While the present invention has been described with reference to theparticular illustrative embodiments, it is not to be restricted by thoseembodiments but only by the appended claims. It is to be appreciatedthat those skilled in the art can change or modify the embodimentswithout departing from the scope and spirit of the present invention.

We claim:
 1. A double walled pipe for pipe jacking method comprising:aninner pipe; and an outer pipe which is movable relative to said innerpipe in a longitudinal direction of said inner pipe, wherein:there isprovided, between said inner pipe and said outer pipe, a ring membersurrounding the periphery of said inner pipe, said ring member beingfixed to said inner pipe, said outer pipe is supported in such a waythat it is slidingly movable relative to said ring member, and said ringmember is equipped with a grout hose insertion aperture, and said doublewalled pipe further comprises a grout hose extending through said grouthose insertion aperture in a longitudinal direction of said doublewalled pipe.
 2. A double walled pipe for pipe jacking methodcomprising:an inner pipe; and an outer pipe which is movable relative tosaid inner pipe in a longitudinal direction of said inner pipe,wherein:there is provided, between said inner pipe and said outer pipe,a ring member surrounding the periphery of said inner pipe, said ringmember being fixed to said inner pipe, said outer pipe is supported insuch a way that it is slidingly movable relative to said ring member,said ring member is equipped with an insertion opening into which agrout hose insertion tube is inserted, and said double walled pipefurther comprises a grout hose insertion tube having a filling materialflow hole, extending through said insertion opening in a longitudinaldirection of said double walled pipe.
 3. A double walled pipe for pipejacking method comprising:an inner pipe; and an outer pipe which ismovable relative to said inner pipe in a longitudinal direction of saidinner pipe, wherein:there is provided, between said inner pipe and saidouter pipe, a ring member surrounding the periphery of said inner pipe,said ring member being fixed to said inner pipe, said outer pipe issupported in such a way that it is slidingly movable relative to saidring member, said ring member is equipped with an insertion opening intowhich a grout hose insertion tube is inserted, said double walled pipefurther comprises a grout hose insertion tube having a filling materialflow hole, extending through said insertion opening in a longitudinaldirection of said double walled pipe, and said grout hose insertion tubeis equipped with said filling material flow hole at the front endportion and/or the back end portion of said grout hose insertion tube.4. A jacking method of propelling underground through a side wall of ashaft a double walled pipe comprising an inner pipe, and an outer pipewhich is movable relative to said inner pipe in a longitudinal directionof said inner pipe, comprising the steps of:connecting a back endportion of an inner pipe of a preceding double walled pipe of which arear end projects to the shaft with a from end portion of an inner pipeof a subsequent double walled pipe to be newly propelled; movingforwards said outer pipe of the subsequent double walled pipe withrespect to said inner pipe to couple a front end plane of said outerpipe of the subsequent double walled pipe with a back end plane of saidouter pipe of the preceding double walled pipe; and propellingunderground the subsequent double walled pipe upon applying a propellingpower on said outer pipe of the subsequent double walled pipe, butapplying no propelling power on said inner pipe of the subsequent doublewalled pipe.
 5. A jacking method according to claim 4, wherein saiddouble walled pipe further comprising a material, provided between saidinner pipe and said outer pipe, for covering the periphery of said innerpipe in such a manner that the front end portion and back end portion ofsaid inner pipe are exposed, and a grout hose insertion hole extendingin a longitudinal direction, said method further comprising the stepsof:connecting a rear end of a grout hose exposed from an opening of aback end of said grout hose insertion hole of a preceding double walledpipe with a tip of a grout hose exposed from an opening of a front endof said grout hose insertion hole of a subsequent double walled pipe,said grout hose connection step being conducted between said inner pipeconnection step and said outer pipe moving step; and filling with afilling material a space between said inner pipes and said outer pipesof the connected double walled pipes each other, by means of slushingthe filling material into the connected grout hoses each other, afterrepetition of said inner pipe connection step, said grout hoseconnection step, said outer pipe moving step and said pipe propellingstep in connection with a plurality of said double walled pipes.
 6. Ajacking method according to claim 5, wherein in said filling step, thefilling is executed in such a manner that while the connected grouthoses each other are sequentially drawn, the rear end of the grout hosesis sequentially positioned at the connected portions of said connecteddouble walled pipes so that the connected portions are filled with thefilling material.
 7. A jacking method according to claim 6, wherein inmid course of the repetition of said inner pipe connection step, saidgrout hose connection step, said outer pipe moving step and said pipepropelling step in connection with a plurality of said double walledpipes, there is set up, after said inner pipe connection step, a step ofexecuting said outer pipe moving step omitting said grout hoseconnection step; andwherein in said filling step, the grout hoses aredrawn from both sides of the front and rear of pipe jacking direction.8. A jacking method according to claim 6, wherein said inner pipeconnection step, said outer pipe moving step and said pipe propellingstep are repeatedly executed in connection with a plurality of saiddouble walled pipes, so that there is formed such a state that a backend portion of an outer pipe of said double walled pipe finally coupledis exposed in said shaft while said inner pipe is projected by apredetermined length from the back end portion of said outer pipe;theback end portion of said double walled pipe finally coupled, which takessaid state, is capped with a protection cap of which one end is closedwith a cover, said protection tube having a diameter same as the outerpipe and a depth exceeding said predetermined length; a bearing wall isconstructed for covering the back end portion of said double walled pipefinally coupled, which takes said state, and said protection cap withwhich said back end portion is capped, said bearing wall being contactwith said side wall; and said inner pipe connection step, said outerpipe moving step and said pipe jacking step are repeatedly executed inconnection with a plurality of said subsequent double walled pipes,while causing said bearing wall to bear a reaction force of apropulsion, so that the plurality of said subsequent double walled pipesare propelled underground from a side wall which is located over againstsaid side wall.
 9. A jacking method according to claim 8, wherein beforethe back end portion of said double walled pipe finally coupled, whichtakes said state, is capped with the protection tube, a back end portionof an inner pipe of said double walled pipe finally coupled is cappedwith a protection cap which is spaced from the protection tube wheninstalled.
 10. A double walled pipe for pipe jacking methodcomprising:an inner pipe; and an outer pipe which is movable relative tosaid inner pipe in a longitudinal direction of said inner pipe,wherein:a front end portion or a back end portion of said outer pipe isequipped with a guide member for guiding a tip of said outer pipe to bemoved relative to said inner pipe, said guide member being adapted toconduct an effective coupling of a preceding double walled pipe with asubsequent double walled pipe, said guide member includes:a ring memberhaving a pan inserted into one end of said outer pipe and fixed to saidouter pipe and other part to be inserted into another outer pipe whichis to be coupled with said outer pipe, said other part being projectedfrom said outer pipe in a longitudinal direction of said outer pipe andbeing provided with a groove surrounding the periphery of the ringmember, wherein said ring member is formed, at a tip end to be insertedinto said other outer pipe, with a taper section which is graduallyreduced toward the tip end; and an O-ring having a flexibility forsealing a coupling portion of outer pipe-to-outer pipe, said O-ringbeing engaged with said groove, and said outer pipe is equipped with acheck valve for permitting a one-way flow from an interior of said outerpipe towards an exterior.
 11. A double walled pipe for pipe jackingmethod comprising:an inner pipe; and an outer pipe which is movablerelative to said inner pipe in a longitudinal direction of said innerpipe, wherein:a front end portion or a back end portion of said outerpipe is equipped with a guide member for guiding a tip of said outerpipe to be moved relative to said inner pipe, said guide member beingadapted to conduct an effective coupling of a preceding double walledpipe with a subsequent double walled pipe, said guide member includes:aring member having a part inserted into one end of said outer pipe andfixed to said outer pipe and other part to be inserted into anotherouter pipe which is to be coupled with said outer pipe, said other partbeing projected from said outer pipe in a longitudinal direction of saidouter pipe and being provided with a groove surrounding the periphery ofthe ring member, wherein said ring member is formed, at a tip end to beinserted into said other outer pipe, with a taper section which iscontinuously reduced in its outside diameter toward the tip end; and anO-ring having a flexibility for sealing a coupling portion of outerpipe-to-outer pipe, said O-ring being engaged with said groove, and saidouter pipe is equipped with a check valve for permitting a one-way flowfrom an interior of said outer pipe towards an exterior.